Install stream extras lazily

js/src/builtin/Stream.cpp

@@ -932,6 +932,13 @@ CallStreamExtra(JSContext* cx, const char* name, HandleValue streamVal,
     if (!JS_GetProperty(cx, global, name, &fun))
         return false;
 
+    if (!fun.isObject() || !IsCallable(fun)) {
+        if (!InitStreamExtras(cx, global))
+            return false;
+        if (!JS_GetProperty(cx, global, name, &fun))
+            return false;
+    }
+
     if (!fun.isObject() || !IsCallable(fun)) {
         JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                   JSMSG_READABLESTREAM_METHOD_NOT_IMPLEMENTED, name);

js/src/jsapi.cpp

@@ -951,6 +951,20 @@ LookupStdName(const JSAtomState& names, JSAtom* name, const JSStdName* table)
     return nullptr;
 }
 
+static bool
+IsStreamExtraName(JSFlatString* name)
+{
+    return JS_FlatStringEqualsAscii(name, "WritableStream") ||
+           JS_FlatStringEqualsAscii(name, "WritableStreamDefaultWriter") ||
+           JS_FlatStringEqualsAscii(name, "WritableStreamDefaultController") ||
+           JS_FlatStringEqualsAscii(name, "TransformStream") ||
+           JS_FlatStringEqualsAscii(name, "TransformStreamDefaultController") ||
+           JS_FlatStringEqualsAscii(name, "TextEncoderStream") ||
+           JS_FlatStringEqualsAscii(name, "TextDecoderStream") ||
+           JS_FlatStringEqualsAscii(name, "CompressionStream") ||
+           JS_FlatStringEqualsAscii(name, "DecompressionStream");
+}
+
 /*
  * Table of standard classes, indexed by JSProtoKey. For entries where the
  * JSProtoKey does not correspond to a class with a meaningful constructor, we
@@ -1041,11 +1055,27 @@ JS_ResolveStandardClass(JSContext* cx, HandleObject obj, HandleId id, bool* reso
             if (!GlobalObject::ensureConstructor(cx, global, key))
                 return false;
 
+            if (key == JSProto_ReadableStream) {
+                RootedObject globalObj(cx, global);
+                if (!InitStreamExtras(cx, globalObj))
+                    return false;
+            }
+
             *resolved = true;
             return true;
         }
     }
 
+    if (cx->options().streams() && IsStreamExtraName(idAtom)) {
+        RootedObject globalObj(cx, global);
+        if (!InitStreamExtras(cx, globalObj))
+            return false;
+
+        if (!HasOwnProperty(cx, globalObj, id, resolved))
+            return false;
+        return true;
+    }
+
     // There is no such property to resolve. An ordinary resolve hook would
     // just return true at this point. But the global object is special in one
     // more way: its prototype chain is lazily initialized. That is,
@@ -1075,6 +1105,7 @@ JS_MayResolveStandardClass(const JSAtomState& names, jsid id, JSObject* maybeObj
 
     return atom == names.undefined ||
            atom == names.globalThis ||
+           IsStreamExtraName(atom) ||
            LookupStdName(names, atom, standard_class_names) ||
            LookupStdName(names, atom, builtin_property_names);
 }

js/src/vm/GlobalObject.cpp

@@ -465,9 +465,6 @@ GlobalObject::initStandardClasses(JSContext* cx, Handle<GlobalObject*> global)
             return false;
     }
 
-    if (cx->options().streams() && !InitStreamExtras(cx, global))
-        return false;
-
     return true;
 }