diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
index 1153b0896f..3d3f5ce670 100644
--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -1060,7 +1060,7 @@ BytecodeEmitter::checkSideEffects(ParseNode* pn, bool* answer)
       case PNK_RAW_UNDEFINED:
       case PNK_ELISION:
       case PNK_GENERATOR:
-        MOZ_ASSERT(pn->isArity(PN_NULLARY));
+        MOZ_ASSERT(pn->is<NullaryNode>());
         *answer = false;
         return true;
 
@@ -1096,9 +1096,17 @@ BytecodeEmitter::checkSideEffects(ParseNode* pn, bool* answer)
         return true;
 
       case PNK_BREAK:
+        MOZ_ASSERT(pn->is<BreakStatement>());
+        *answer = true;
+        return true;
+
       case PNK_CONTINUE:
+        MOZ_ASSERT(pn->is<ContinueStatement>());
+        *answer = true;
+        return true;
+
       case PNK_DEBUGGER:
-        MOZ_ASSERT(pn->isArity(PN_NULLARY));
+        MOZ_ASSERT(pn->is<DebuggerStatement>());
         *answer = true;
         return true;
 
diff --git a/js/src/frontend/FoldConstants.cpp b/js/src/frontend/FoldConstants.cpp
index fcc94c34fa..a5383c1c7c 100644
--- a/js/src/frontend/FoldConstants.cpp
+++ b/js/src/frontend/FoldConstants.cpp
@@ -101,8 +101,12 @@ ContainsHoistedDeclaration(ExclusiveContext* cx, ParseNode* node, bool* result)
 
       // Statements with no sub-components at all.
       case PNK_NOP: // induced by function f() {} function f() {}
+        MOZ_ASSERT(node->is<NullaryNode>());
+        *result = false;
+        return true;
+
       case PNK_DEBUGGER:
-        MOZ_ASSERT(node->isArity(PN_NULLARY));
+        MOZ_ASSERT(node->is<DebuggerStatement>());
         *result = false;
         return true;
 
@@ -1655,13 +1659,22 @@ Fold(ExclusiveContext* cx, ParseNode** pnp, Parser<FullParseHandler>& parser, bo
       case PNK_NULL:
       case PNK_RAW_UNDEFINED:
       case PNK_ELISION:
-      case PNK_DEBUGGER:
-      case PNK_BREAK:
-      case PNK_CONTINUE:
       case PNK_GENERATOR:
       case PNK_EXPORT_BATCH_SPEC:
       case PNK_POSHOLDER:
-        MOZ_ASSERT(pn->isArity(PN_NULLARY));
+        MOZ_ASSERT(pn->is<NullaryNode>());
+        return true;
+
+      case PNK_DEBUGGER:
+        MOZ_ASSERT(pn->is<DebuggerStatement>());
+        return true;
+
+      case PNK_BREAK:
+        MOZ_ASSERT(pn->is<BreakStatement>());
+        return true;
+
+      case PNK_CONTINUE:
+        MOZ_ASSERT(pn->is<ContinueStatement>());
         return true;
 
       case PNK_OBJECT_PROPERTY_NAME:
diff --git a/js/src/frontend/FullParseHandler.h b/js/src/frontend/FullParseHandler.h
index dca7a69cf2..6b81d153ab 100644
--- a/js/src/frontend/FullParseHandler.h
+++ b/js/src/frontend/FullParseHandler.h
@@ -151,7 +151,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         return new_<NumericLiteral>(value, decimalPoint, pos);
     }
 
-    ParseNode* newBooleanLiteral(bool cond, const TokenPos& pos) {
+    BooleanLiteralType newBooleanLiteral(bool cond, const TokenPos& pos) {
         return new_<BooleanLiteral>(cond, pos);
     }
 
@@ -195,11 +195,11 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         return new_<ThisLiteral>(pos, thisName);
     }
 
-    ParseNode* newNullLiteral(const TokenPos& pos) {
+    NullLiteralType newNullLiteral(const TokenPos& pos) {
         return new_<NullLiteral>(pos);
     }
 
-    ParseNode* newRawUndefinedLiteral(const TokenPos& pos) {
+    RawUndefinedLiteralType newRawUndefinedLiteral(const TokenPos& pos) {
         return new_<RawUndefinedLiteral>(pos);
     }
 
@@ -251,7 +251,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         return new_<UnaryNode>(kind, JSOP_NOP, pos, kid);
     }
 
-    ParseNode* newNullary(ParseNodeKind kind, JSOp op, const TokenPos& pos) {
+    NullaryNodeType newNullary(ParseNodeKind kind, JSOp op, const TokenPos& pos) {
         return new_<NullaryNode>(kind, op, pos);
     }
 
@@ -311,7 +311,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
     }
 
     MOZ_MUST_USE bool addElision(ListNodeType literal, const TokenPos& pos) {
-        ParseNode* elision = new_<NullaryNode>(PNK_ELISION, pos);
+        NullaryNode* elision = new_<NullaryNode>(PNK_ELISION, pos);
         if (!elision)
             return false;
         literal->append(elision);
@@ -377,10 +377,10 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
     ClassNamesType newClassNames(ParseNode* outer, ParseNode* inner, const TokenPos& pos) {
         return new_<ClassNames>(outer, inner, pos);
     }
-    BinaryNodeType newNewTarget(ParseNode* newHolder, ParseNode* targetHolder) {
+    BinaryNodeType newNewTarget(NullaryNodeType newHolder, NullaryNodeType targetHolder) {
         return new_<BinaryNode>(PNK_NEWTARGET, JSOP_NOP, newHolder, targetHolder);
     }
-    ParseNode* newPosHolder(const TokenPos& pos) {
+    NullaryNodeType newPosHolder(const TokenPos& pos) {
         return new_<NullaryNode>(PNK_POSHOLDER, pos);
     }
     UnaryNodeType newSuperBase(Node thisName, const TokenPos& pos) {
@@ -536,7 +536,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         MOZ_ASSERT(stmtList->isKind(PNK_STATEMENTLIST));
 
         TokenPos yieldPos(stmtList->pn_pos.begin, stmtList->pn_pos.begin + 1);
-        ParseNode* makeGen = new_<NullaryNode>(PNK_GENERATOR, yieldPos);
+        NullaryNode* makeGen = new_<NullaryNode>(PNK_GENERATOR, yieldPos);
         if (!makeGen)
             return false;
 
@@ -560,7 +560,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         return newBinary(PNK_SETTHIS, thisName, val);
     }
 
-    ParseNode* newEmptyStatement(const TokenPos& pos) {
+    UnaryNodeType newEmptyStatement(const TokenPos& pos) {
         return new_<UnaryNode>(PNK_SEMI, JSOP_NOP, pos, (ParseNode*) nullptr);
     }
 
@@ -657,11 +657,11 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         return new_<CaseClause>(expr, body, begin);
     }
 
-    ParseNode* newContinueStatement(PropertyName* label, const TokenPos& pos) {
+    ContinueStatementType newContinueStatement(PropertyName* label, const TokenPos& pos) {
         return new_<ContinueStatement>(label, pos);
     }
 
-    ParseNode* newBreakStatement(PropertyName* label, const TokenPos& pos) {
+    BreakStatementType newBreakStatement(PropertyName* label, const TokenPos& pos) {
         return new_<BreakStatement>(label, pos);
     }
 
@@ -690,7 +690,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         return new_<TernaryNode>(PNK_TRY, JSOP_NOP, body, catchList, finallyBlock, pos);
     }
 
-    ParseNode* newDebuggerStatement(const TokenPos& pos) {
+    DebuggerStatementType newDebuggerStatement(const TokenPos& pos) {
         return new_<DebuggerStatement>(pos);
     }
 
diff --git a/js/src/frontend/NameFunctions.cpp b/js/src/frontend/NameFunctions.cpp
index 92a97ae8b7..affad7a239 100644
--- a/js/src/frontend/NameFunctions.cpp
+++ b/js/src/frontend/NameFunctions.cpp
@@ -388,12 +388,21 @@ class NameResolver
           case PNK_RAW_UNDEFINED:
           case PNK_ELISION:
           case PNK_GENERATOR:
-          case PNK_BREAK:
-          case PNK_CONTINUE:
-          case PNK_DEBUGGER:
           case PNK_EXPORT_BATCH_SPEC:
           case PNK_POSHOLDER:
-            MOZ_ASSERT(cur->isArity(PN_NULLARY));
+            MOZ_ASSERT(cur->is<NullaryNode>());
+            break;
+
+          case PNK_DEBUGGER:
+            MOZ_ASSERT(cur->is<DebuggerStatement>());
+            break;
+
+          case PNK_BREAK:
+            MOZ_ASSERT(cur->is<BreakStatement>());
+            break;
+
+          case PNK_CONTINUE:
+            MOZ_ASSERT(cur->is<ContinueStatement>());
             break;
 
           case PNK_OBJECT_PROPERTY_NAME:
@@ -801,7 +810,7 @@ class NameResolver
             ListNode* list = &cur->as<ListNode>();
             ParseNode* item = list->head();
             if (!isImport && item && item->isKind(PNK_EXPORT_BATCH_SPEC)) {
-                MOZ_ASSERT(item->isArity(PN_NULLARY));
+                MOZ_ASSERT(item->is<NullaryNode>());
                 break;
             }
             for (ParseNode* item : list->contents()) {
diff --git a/js/src/frontend/ParseNode.cpp b/js/src/frontend/ParseNode.cpp
index 5b1a838c47..0e1492f0eb 100644
--- a/js/src/frontend/ParseNode.cpp
+++ b/js/src/frontend/ParseNode.cpp
@@ -183,14 +183,23 @@ PushNodeChildren(ParseNode* pn, NodeStack* stack)
       case PNK_RAW_UNDEFINED:
       case PNK_ELISION:
       case PNK_GENERATOR:
-      case PNK_BREAK:
-      case PNK_CONTINUE:
-      case PNK_DEBUGGER:
       case PNK_EXPORT_BATCH_SPEC:
       case PNK_POSHOLDER:
-        MOZ_ASSERT(pn->isArity(PN_NULLARY));
+        MOZ_ASSERT(pn->is<NullaryNode>());
         return PushResult::Recyclable;
 
+      case PNK_DEBUGGER:
+          MOZ_ASSERT(pn->is<DebuggerStatement>());
+          return PushResult::Recyclable;
+
+      case PNK_BREAK:
+          MOZ_ASSERT(pn->is<BreakStatement>());
+          return PushResult::Recyclable;
+
+      case PNK_CONTINUE:
+          MOZ_ASSERT(pn->is<ContinueStatement>());
+          return PushResult::Recyclable;
+
       case PNK_OBJECT_PROPERTY_NAME:
       case PNK_STRING:
       case PNK_TEMPLATE_STRING:
@@ -662,7 +671,7 @@ ParseNode::dump(int indent)
 {
     switch (pn_arity) {
       case PN_NULLARY:
-        ((NullaryNode*) this)->dump();
+        as<NullaryNode>().dump();
         return;
       case PN_UNARY:
         as<UnaryNode>().dump(indent);
@@ -688,6 +697,9 @@ ParseNode::dump(int indent)
       case PN_REGEXP:
         as<RegExpLiteral>().dump(indent);
         return;
+      case PN_LOOP:
+        as<LoopControlStatement>().dump(indent);
+        return;
       case PN_SCOPE:
         ((LexicalScopeNode*) this)->dump(indent);
         return;
@@ -731,6 +743,18 @@ RegExpLiteral::dump(int indent)
     fprintf(stderr, "(%s)", parseNodeNames[size_t(getKind())]);
 }
 
+void
+LoopControlStatement::dump(int indent)
+{
+    const char* name = parseNodeNames[size_t(getKind())];
+    fprintf(stderr, "(%s", name);
+    if (label()) {
+        fprintf(stderr, " ");
+        label()->dumpCharsNoNewline();
+    }
+    fprintf(stderr, ")");
+}
+
 void
 UnaryNode::dump(int indent)
 {
diff --git a/js/src/frontend/ParseNode.h b/js/src/frontend/ParseNode.h
index f00e370e6f..12d79ab4f8 100644
--- a/js/src/frontend/ParseNode.h
+++ b/js/src/frontend/ParseNode.h
@@ -321,9 +321,9 @@ IsTypeofKind(ParseNodeKind kind)
  *   kid2: null or the catch guard expression
  *   kid3: catch block statements
  * PNK_BREAK (BreakStatement)
- *   atom: label or null
+ *   label: label or null
  * PNK_CONTINUE (ContinueStatement)
- *   atom: label or null
+ *   label: label or null
  * PNK_WITH (BinaryNode)
  *   left: head expr
  *   right: body
@@ -506,10 +506,12 @@ IsTypeofKind(ParseNodeKind kind)
  *   regexp: RegExp model object
  * PNK_NUMBER (NumericLiteral)
  *   value: double value of numeric literal
- * PNK_TRUE,    nullary     pn_op: JSOp bytecode
- * PNK_FALSE,
- * PNK_NULL,
- * PNK_RAW_UNDEFINED
+ * PNK_TRUE, PNK_FALSE (BooleanLiteral)
+ *   pn_op: JSOp bytecode
+ * PNK_NULL (NullLiteral)
+ *   pn_op: JSOp bytecode
+ * PNK_RAW_UNDEFINED (RawUndefinedLiteral)
+ *   pn_op: JSOp bytecode
  *
  * PNK_THIS (UnaryNode)
  *   kid: '.this' Name if function `this`, else nullptr
@@ -524,7 +526,7 @@ IsTypeofKind(ParseNodeKind kind)
  *   right: SuperCall
  * PNK_LEXICALSCOPE scope   pn_u.scope.bindings: scope bindings
  *                          pn_u.scope.body: scope body
- * PNK_GENERATOR    nullary
+ * PNK_GENERATOR (NullaryNode)
  * PNK_INITIALYIELD (UnaryNode)
  *   kid: generator object
  * PNK_YIELD, PNK_YIELD_STAR, PNK_AWAIT (UnaryNode)
@@ -535,7 +537,7 @@ IsTypeofKind(ParseNodeKind kind)
  *                          if-guarded PNK_ARRAYPUSH
  * PNK_ARRAYPUSH    unary   pn_op: JSOP_ARRAYCOMP
  *                          pn_kid: array comprehension expression
- * PNK_NOP          nullary
+ * PNK_NOP (NullaryNode)
  */
 enum ParseNodeArity
 {
@@ -548,6 +550,7 @@ enum ParseNodeArity
     PN_NAME,                            /* name, label, string */
     PN_NUMBER,                          /* numeric literal */
     PN_REGEXP,                          /* regexp literal */
+    PN_LOOP,                            /* loop control (break/continue) */
     PN_SCOPE                            /* lexical scope */
 };
 
@@ -567,9 +570,19 @@ enum ParseNodeArity
     macro(ListNode, ListNodeType, asList) \
     macro(CallSiteNode, CallSiteNodeType, asCallSite) \
     \
+    macro(LoopControlStatement, LoopControlStatementType, asLoopControlStatement) \
+    macro(BreakStatement, BreakStatementType, asBreakStatement) \
+    macro(ContinueStatement, ContinueStatementType, asContinueStatement) \
+    \
     macro(NameNode, NameNodeType, asName) \
     macro(LabeledStatement, LabeledStatementType, asLabeledStatement) \
     \
+    macro(NullaryNode, NullaryNodeType, asNullary) \
+    macro(BooleanLiteral, BooleanLiteralType, asBooleanLiteral) \
+    macro(DebuggerStatement, DebuggerStatementType, asDebuggerStatement) \
+    macro(NullLiteral, NullLiteralType, asNullLiteral) \
+    macro(RawUndefinedLiteral, RawUndefinedLiteralType, asRawUndefinedLiteral) \
+    \
     macro(NumericLiteral, NumericLiteralType, asNumericLiteral) \
     \
     macro(RegExpLiteral, RegExpLiteralType, asRegExpLiteral) \
@@ -580,10 +593,6 @@ enum ParseNodeArity
     macro(UnaryNode, UnaryNodeType, asUnary) \
     macro(ThisLiteral, ThisLiteralType, asThisLiteral)
 
-class LoopControlStatement;
-class BreakStatement;
-class ContinueStatement;
-
 #define DECLARE_CLASS(typeName, longTypeName, asMethodName) \
 class typeName;
 FOR_EACH_PARSENODE_SUBCLASS(DECLARE_CLASS)
@@ -733,6 +742,7 @@ class ParseNode
             DecimalPoint decimalPoint;  /* Whether the number has a decimal point */
         } number;
         class {
+          private:
             friend class LoopControlStatement;
             PropertyName*    label;    /* target of break/continue statement */
         } loopControl;
@@ -819,13 +829,18 @@ class ParseNode
 #endif
 };
 
-struct NullaryNode : public ParseNode
+class NullaryNode : public ParseNode
 {
+  public:
     NullaryNode(ParseNodeKind kind, const TokenPos& pos)
       : ParseNode(kind, JSOP_NOP, PN_NULLARY, pos) {}
     NullaryNode(ParseNodeKind kind, JSOp op, const TokenPos& pos)
       : ParseNode(kind, op, PN_NULLARY, pos) {}
 
+    static bool test(const ParseNode& node) {
+        return node.isArity(PN_NULLARY);
+    }
+
 #ifdef DEBUG
     void dump();
 #endif
@@ -1587,7 +1602,7 @@ class LoopControlStatement : public ParseNode
 {
   protected:
     LoopControlStatement(ParseNodeKind kind, PropertyName* label, const TokenPos& pos)
-      : ParseNode(kind, JSOP_NOP, PN_NULLARY, pos)
+      : ParseNode(kind, JSOP_NOP, PN_LOOP, pos)
     {
         MOZ_ASSERT(kind == PNK_BREAK || kind == PNK_CONTINUE);
         pn_u.loopControl.label = label;
@@ -1599,9 +1614,13 @@ class LoopControlStatement : public ParseNode
         return pn_u.loopControl.label;
     }
 
+#ifdef DEBUG
+    void dump(int indent);
+#endif
+
     static bool test(const ParseNode& node) {
         bool match = node.isKind(PNK_BREAK) || node.isKind(PNK_CONTINUE);
-        MOZ_ASSERT_IF(match, node.isArity(PN_NULLARY));
+        MOZ_ASSERT_IF(match, node.isArity(PN_LOOP));
         MOZ_ASSERT_IF(match, node.isOp(JSOP_NOP));
         return match;
     }
@@ -1616,7 +1635,7 @@ class BreakStatement : public LoopControlStatement
 
     static bool test(const ParseNode& node) {
         bool match = node.isKind(PNK_BREAK);
-        MOZ_ASSERT_IF(match, node.isArity(PN_NULLARY));
+        MOZ_ASSERT_IF(match, node.is<LoopControlStatement>());
         MOZ_ASSERT_IF(match, node.isOp(JSOP_NOP));
         return match;
     }
@@ -1631,18 +1650,24 @@ class ContinueStatement : public LoopControlStatement
 
     static bool test(const ParseNode& node) {
         bool match = node.isKind(PNK_CONTINUE);
-        MOZ_ASSERT_IF(match, node.isArity(PN_NULLARY));
+        MOZ_ASSERT_IF(match, node.is<LoopControlStatement>());
         MOZ_ASSERT_IF(match, node.isOp(JSOP_NOP));
         return match;
     }
 };
 
-class DebuggerStatement : public ParseNode
+class DebuggerStatement : public NullaryNode
 {
   public:
     explicit DebuggerStatement(const TokenPos& pos)
-      : ParseNode(PNK_DEBUGGER, JSOP_NOP, PN_NULLARY, pos)
+      : NullaryNode(PNK_DEBUGGER, JSOP_NOP, pos)
     { }
+
+    static bool test(const ParseNode& node) {
+        bool match = node.isKind(PNK_DEBUGGER);
+        MOZ_ASSERT_IF(match, node.is<NullaryNode>());
+        return match;
+    }
 };
 
 class ConditionalExpression : public TernaryNode
@@ -1697,6 +1722,12 @@ class NullLiteral : public NullaryNode
     explicit NullLiteral(const TokenPos& pos)
       : NullaryNode(PNK_NULL, JSOP_NULL, pos)
     { }
+
+    static bool test(const ParseNode& node) {
+        bool match = node.isKind(PNK_NULL);
+        MOZ_ASSERT_IF(match, node.is<NullaryNode>());
+        return match;
+    }
 };
 
 // This is only used internally, currently just for tagged templates.
@@ -1707,6 +1738,12 @@ class RawUndefinedLiteral : public NullaryNode
   public:
     explicit RawUndefinedLiteral(const TokenPos& pos)
       : NullaryNode(PNK_RAW_UNDEFINED, JSOP_UNDEFINED, pos) { }
+
+    static bool test(const ParseNode& node) {
+        bool match = node.isKind(PNK_RAW_UNDEFINED);
+        MOZ_ASSERT_IF(match, node.is<NullaryNode>());
+        return match;
+    }
 };
 
 class BooleanLiteral : public NullaryNode
@@ -1715,6 +1752,12 @@ class BooleanLiteral : public NullaryNode
     BooleanLiteral(bool b, const TokenPos& pos)
       : NullaryNode(b ? PNK_TRUE : PNK_FALSE, b ? JSOP_TRUE : JSOP_FALSE, pos)
     { }
+
+    static bool test(const ParseNode& node) {
+        bool match = node.isKind(PNK_TRUE) || node.isKind(PNK_FALSE);
+        MOZ_ASSERT_IF(match, node.is<NullaryNode>());
+        return match;
+    }
 };
 
 class RegExpLiteral : public ParseNode
diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index 974cbae36c..528d57adb2 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -5469,7 +5469,7 @@ Parser<ParseHandler>::exportBatch(uint32_t begin)
 
     // Handle the form |export *| by adding a special export batch
     // specifier to the list.
-    Node exportSpec = handler.newNullary(PNK_EXPORT_BATCH_SPEC, JSOP_NOP, pos());
+    NullaryNodeType exportSpec = handler.newNullary(PNK_EXPORT_BATCH_SPEC, JSOP_NOP, pos());
     if (!exportSpec)
         return null();
 
@@ -6542,7 +6542,7 @@ Parser<ParseHandler>::switchStatement(YieldHandling yieldHandling)
 }
 
 template <typename ParseHandler>
-typename ParseHandler::Node
+typename ParseHandler::ContinueStatementType
 Parser<ParseHandler>::continueStatement(YieldHandling yieldHandling)
 {
     MOZ_ASSERT(tokenStream.isCurrentTokenType(TOK_CONTINUE));
@@ -6600,7 +6600,7 @@ Parser<ParseHandler>::continueStatement(YieldHandling yieldHandling)
 }
 
 template <typename ParseHandler>
-typename ParseHandler::Node
+typename ParseHandler::BreakStatementType
 Parser<ParseHandler>::breakStatement(YieldHandling yieldHandling)
 {
     MOZ_ASSERT(tokenStream.isCurrentTokenType(TOK_BREAK));
@@ -7192,7 +7192,7 @@ Parser<ParseHandler>::catchBlockStatement(YieldHandling yieldHandling,
 }
 
 template <typename ParseHandler>
-typename ParseHandler::Node
+typename ParseHandler::DebuggerStatementType
 Parser<ParseHandler>::debuggerStatement()
 {
     TokenPos p;
@@ -10378,7 +10378,7 @@ Parser<ParseHandler>::tryNewTarget(BinaryNodeType* newTarget)
 
     *newTarget = null();
 
-    Node newHolder = handler.newPosHolder(pos());
+    NullaryNodeType newHolder = handler.newPosHolder(pos());
     if (!newHolder)
         return false;
 
@@ -10406,7 +10406,7 @@ Parser<ParseHandler>::tryNewTarget(BinaryNodeType* newTarget)
         return false;
     }
 
-    Node targetHolder = handler.newPosHolder(pos());
+    NullaryNodeType targetHolder = handler.newPosHolder(pos());
     if (!targetHolder)
         return false;
 
diff --git a/js/src/frontend/Parser.h b/js/src/frontend/Parser.h
index 0ab23ef578..0a52c18701 100644
--- a/js/src/frontend/Parser.h
+++ b/js/src/frontend/Parser.h
@@ -1211,14 +1211,14 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_TYPE)
     Node expressionAfterForInOrOf(ParseNodeKind forHeadKind, YieldHandling yieldHandling);
 
     SwitchStatementType switchStatement(YieldHandling yieldHandling);
-    Node continueStatement(YieldHandling yieldHandling);
-    Node breakStatement(YieldHandling yieldHandling);
+    ContinueStatementType continueStatement(YieldHandling yieldHandling);
+    BreakStatementType breakStatement(YieldHandling yieldHandling);
     UnaryNodeType returnStatement(YieldHandling yieldHandling);
     BinaryNodeType withStatement(YieldHandling yieldHandling);
     UnaryNodeType throwStatement(YieldHandling yieldHandling);
     TernaryNodeType tryStatement(YieldHandling yieldHandling);
     Node catchBlockStatement(YieldHandling yieldHandling, ParseContext::Scope& catchParamScope);
-    Node debuggerStatement();
+    DebuggerStatementType debuggerStatement();
 
     Node variableStatement(YieldHandling yieldHandling);
 
diff --git a/js/src/frontend/SyntaxParseHandler.h b/js/src/frontend/SyntaxParseHandler.h
index fd7753c581..dc59e7da93 100644
--- a/js/src/frontend/SyntaxParseHandler.h
+++ b/js/src/frontend/SyntaxParseHandler.h
@@ -224,7 +224,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
     }
 
     NumericLiteralType newNumber(double value, DecimalPoint decimalPoint, const TokenPos& pos) { return NodeGeneric; }
-    Node newBooleanLiteral(bool cond, const TokenPos& pos) { return NodeGeneric; }
+    BooleanLiteralType newBooleanLiteral(bool cond, const TokenPos& pos) { return NodeGeneric; }
 
     NameNodeType newStringLiteral(JSAtom* atom, const TokenPos& pos) {
         lastAtom = atom;
@@ -243,8 +243,8 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
     void addToCallSiteObject(CallSiteNodeType callSiteObj, Node rawNode, Node cookedNode) {}
 
     UnaryNodeType newThisLiteral(const TokenPos& pos, Node thisName) { return NodeGeneric; }
-    Node newNullLiteral(const TokenPos& pos) { return NodeGeneric; }
-    Node newRawUndefinedLiteral(const TokenPos& pos) { return NodeGeneric; }
+    NullLiteralType newNullLiteral(const TokenPos& pos) { return NodeGeneric; }
+    RawUndefinedLiteralType newRawUndefinedLiteral(const TokenPos& pos) { return NodeGeneric; }
 
     template <class Boxer>
     RegExpLiteralType newRegExp(RegExpObject* reobj, const TokenPos& pos, Boxer& boxer) { return NodeGeneric; }
@@ -263,7 +263,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         return NodeUnparenthesizedUnary;
     }
 
-    Node newNullary(ParseNodeKind kind, JSOp op, const TokenPos& pos) {
+    NullaryNodeType newNullary(ParseNodeKind kind, JSOp op, const TokenPos& pos) {
         return NodeGeneric;
     }
 
@@ -316,8 +316,10 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
     ClassNamesType newClassNames(Node outer, Node inner, const TokenPos& pos) { return NodeGeneric; }
     ClassNodeType newClass(Node name, Node heritage, Node methodBlock, const TokenPos& pos) { return NodeGeneric; }
 
-    BinaryNodeType newNewTarget(Node newHolder, Node targetHolder) { return NodeGeneric; }
-    Node newPosHolder(const TokenPos& pos) { return NodeGeneric; }
+    BinaryNodeType newNewTarget(NullaryNodeType newHolder, NullaryNodeType targetHolder) {
+        return NodeGeneric;
+    }
+    NullaryNodeType newPosHolder(const TokenPos& pos) { return NodeGeneric; }
     UnaryNodeType newSuperBase(Node thisName, const TokenPos& pos) { return NodeSuperBase; }
 
     MOZ_MUST_USE bool addPrototypeMutation(ListNodeType literal, uint32_t begin, Node expr) { return true; }
@@ -337,7 +339,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
     void addStatementToList(ListNodeType list, Node stmt) {}
     void addCaseStatementToList(ListNodeType list, CaseClauseType caseClause) {}
     MOZ_MUST_USE bool prependInitialYield(ListNodeType stmtList, Node genName) { return true; }
-    Node newEmptyStatement(const TokenPos& pos) { return NodeEmptyStatement; }
+    UnaryNodeType newEmptyStatement(const TokenPos& pos) { return NodeEmptyStatement; }
 
     UnaryNodeType newExportDeclaration(Node kid, const TokenPos& pos) {
         return NodeGeneric;
@@ -365,8 +367,8 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
         return NodeGeneric;
     }
     CaseClauseType newCaseOrDefault(uint32_t begin, Node expr, Node body) { return NodeGeneric; }
-    Node newContinueStatement(PropertyName* label, const TokenPos& pos) { return NodeGeneric; }
-    Node newBreakStatement(PropertyName* label, const TokenPos& pos) { return NodeBreak; }
+    ContinueStatementType newContinueStatement(PropertyName* label, const TokenPos& pos) { return NodeGeneric; }
+    BreakStatementType newBreakStatement(PropertyName* label, const TokenPos& pos) { return NodeBreak; }
     UnaryNodeType newReturnStatement(Node expr, const TokenPos& pos) { return NodeReturn; }
     BinaryNodeType newWithStatement(uint32_t begin, Node expr, Node body) { return NodeGeneric; }
 
@@ -378,7 +380,7 @@ FOR_EACH_PARSENODE_SUBCLASS(DECLARE_AS)
     Node newTryStatement(uint32_t begin, Node body, ListNodeType catchList, Node finallyBlock) {
         return NodeGeneric;
     }
-    Node newDebuggerStatement(const TokenPos& pos) { return NodeGeneric; }
+    DebuggerStatementType newDebuggerStatement(const TokenPos& pos) { return NodeGeneric; }
 
     NameNodeType newPropertyName(PropertyName* name, const TokenPos& pos) {
         lastAtom = name;
diff --git a/js/src/wasm/AsmJS.cpp b/js/src/wasm/AsmJS.cpp
index 739bf3e01c..ff943aed40 100644
--- a/js/src/wasm/AsmJS.cpp
+++ b/js/src/wasm/AsmJS.cpp
@@ -598,7 +598,6 @@ static inline PropertyName*
 LoopControlMaybeLabel(ParseNode* pn)
 {
     MOZ_ASSERT(pn->isKind(PNK_BREAK) || pn->isKind(PNK_CONTINUE));
-    MOZ_ASSERT(pn->isArity(PN_NULLARY));
     return pn->as<LoopControlStatement>().label();
 }