diff --git a/devtools/client/shared/widgets/VariablesView.jsm b/devtools/client/shared/widgets/VariablesView.jsm
index 2ba8d74916..fc9d084363 100644
--- a/devtools/client/shared/widgets/VariablesView.jsm
+++ b/devtools/client/shared/widgets/VariablesView.jsm
@@ -908,6 +908,10 @@ VariablesView.prototype = {
       // Copy current selection to clipboard.
       if (e.ctrlKey || e.metaKey) {
         let item = this.getFocusedItem();
+        if (!item) {
+          // No item is selected; do nothing.
+          return;
+        }
         clipboardHelper.copyString(
           item._nameString + item.separatorStr + item._valueString
         );
diff --git a/devtools/shared/css/generated/properties-db.js b/devtools/shared/css/generated/properties-db.js
index d9b5ee65b7..fb95ffd1f1 100644
--- a/devtools/shared/css/generated/properties-db.js
+++ b/devtools/shared/css/generated/properties-db.js
@@ -7257,6 +7257,25 @@ exports.CSS_PROPERTIES = {
       "unset"
     ]
   },
+  "margin-block": {
+    "isInherited": false,
+    "subproperties": [
+      "margin-block-start",
+      "margin-block-end"
+    ],
+    "supports": [
+      6,
+      8
+    ],
+    "values": [
+      "-moz-calc",
+      "auto",
+      "calc",
+      "inherit",
+      "initial",
+      "unset"
+    ]
+  },
   "margin-block-end": {
     "isInherited": false,
     "subproperties": [
@@ -7311,6 +7330,25 @@ exports.CSS_PROPERTIES = {
       "unset"
     ]
   },
+  "margin-inline": {
+    "isInherited": false,
+    "subproperties": [
+      "margin-inline-start",
+      "margin-inline-end"
+    ],
+    "supports": [
+      6,
+      8
+    ],
+    "values": [
+      "-moz-calc",
+      "auto",
+      "calc",
+      "inherit",
+      "initial",
+      "unset"
+    ]
+  },
   "margin-inline-end": {
     "isInherited": false,
     "subproperties": [
@@ -8246,6 +8284,24 @@ exports.CSS_PROPERTIES = {
       "unset"
     ]
   },
+  "padding-block": {
+    "isInherited": false,
+    "subproperties": [
+      "padding-block-start",
+      "padding-block-end"
+    ],
+    "supports": [
+      6,
+      8
+    ],
+    "values": [
+      "-moz-calc",
+      "calc",
+      "inherit",
+      "initial",
+      "unset"
+    ]
+  },
   "padding-block-end": {
     "isInherited": false,
     "subproperties": [
@@ -8297,6 +8353,24 @@ exports.CSS_PROPERTIES = {
       "unset"
     ]
   },
+  "padding-inline": {
+    "isInherited": false,
+    "subproperties": [
+      "padding-inline-start",
+      "padding-inline-end"
+    ],
+    "supports": [
+      6,
+      8
+    ],
+    "values": [
+      "-moz-calc",
+      "calc",
+      "inherit",
+      "initial",
+      "unset"
+    ]
+  },
   "padding-inline-end": {
     "isInherited": false,
     "subproperties": [
diff --git a/dom/workers/WorkerRunnable.cpp b/dom/workers/WorkerRunnable.cpp
index eb56650b51..9049878710 100644
--- a/dom/workers/WorkerRunnable.cpp
+++ b/dom/workers/WorkerRunnable.cpp
@@ -231,8 +231,13 @@ WorkerRunnable::Run()
 {
   bool targetIsWorkerThread = mBehavior == WorkerThreadModifyBusyCount ||
                               mBehavior == WorkerThreadUnchangedBusyCount;
+  bool alreadyCanceled = IsCanceled() && !mCallingCancelWithinRun;
+  bool shouldCancelWorker = targetIsWorkerThread &&
+                            mWorkerPrivate->AllPendingRunnablesShouldBeCanceled() &&
+                            !IsCanceled() && !mCallingCancelWithinRun;
+  bool runnableWillRun = !alreadyCanceled && !shouldCancelWorker;
 
-  if (targetIsWorkerThread) {
+  if (targetIsWorkerThread && runnableWillRun) {
     // On a worker thread, a WorkerRunnable should only run when there is an
     // underlying WorkerThreadPrimaryRunnable active, which means we should
     // find a CycleCollectedJSContext.
@@ -256,14 +261,11 @@ WorkerRunnable::Run()
   }
 #endif
 
-  if (IsCanceled() && !mCallingCancelWithinRun) {
+  if (alreadyCanceled) {
     return NS_OK;
   }
 
-  if (targetIsWorkerThread &&
-      mWorkerPrivate->AllPendingRunnablesShouldBeCanceled() &&
-      !IsCanceled() && !mCallingCancelWithinRun) {
-
+  if (shouldCancelWorker) {
     // Prevent recursion.
     mCallingCancelWithinRun = true;
 
diff --git a/layout/style/Declaration.cpp b/layout/style/Declaration.cpp
index ab2def15fa..989e45765c 100644
--- a/layout/style/Declaration.cpp
+++ b/layout/style/Declaration.cpp
@@ -1474,6 +1474,10 @@ Declaration::GetPropertyValueInternal(
       }
       MOZ_FALLTHROUGH;
     }
+    case eCSSProperty_margin_block:
+    case eCSSProperty_margin_inline:
+    case eCSSProperty_padding_block:
+    case eCSSProperty_padding_inline:
     case eCSSProperty_gap: {
       const nsCSSPropertyID* subprops =
         nsCSSProps::SubpropertyEntryFor(aProperty);
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index 494d8f6aa6..2cb6e3ec13 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -1084,12 +1084,16 @@ protected:
   bool ParseListStyle();
   bool ParseListStyleType(nsCSSValue& aValue);
   bool ParseMargin();
+  bool ParseMarginBlock();
+  bool ParseMarginInline();
   bool ParseClipPath(nsCSSValue& aValue);
   bool ParseTransform(bool aIsPrefixed, bool aDisallowRelativeValues = false);
   bool ParseObjectPosition();
   bool ParseOutline();
   bool ParseOverflow();
   bool ParsePadding();
+  bool ParsePaddingBlock();
+  bool ParsePaddingInline();
   bool ParseQuotes();
   bool ParseTextAlign(nsCSSValue& aValue,
                       const KTableEntry aTable[]);
@@ -1188,6 +1192,10 @@ protected:
   // Reused utility parsing routines
   void AppendValue(nsCSSPropertyID aPropID, const nsCSSValue& aValue);
   bool ParseBoxProperties(const nsCSSPropertyID aPropIDs[]);
+  bool ParseBoxPairProperties(int32_t aSingleVariantMask,
+                              int32_t aPairVariantMask,
+                              nsCSSPropertyID aStart,
+                              nsCSSPropertyID aEnd);
   bool ParseGroupedBoxProperty(int32_t aVariantMask,
                                nsCSSValue& aValue,
                                uint32_t aRestrictions);
@@ -10107,25 +10115,10 @@ CSSParserImpl::ParseGridArea()
 bool
 CSSParserImpl::ParseGap()
 {
-  nsCSSValue first;
-  if (ParseSingleTokenVariant(first, VARIANT_INHERIT, nullptr)) {
-    AppendValue(eCSSProperty_row_gap, first);
-    AppendValue(eCSSProperty_column_gap, first);
-    return true;
-  }
-  if (ParseNonNegativeVariant(first, VARIANT_LPCALC, nullptr) !=
-        CSSParseResult::Ok) {
-    return false;
-  }
-  nsCSSValue second;
-  auto result = ParseNonNegativeVariant(second, VARIANT_LPCALC, nullptr);
-  if (result == CSSParseResult::Error) {
-    return false;
-  }
-  AppendValue(eCSSProperty_row_gap, first);
-  AppendValue(eCSSProperty_column_gap,
-              result == CSSParseResult::NotFound ? first : second);
-  return true;
+  return ParseBoxPairProperties(VARIANT_INHERIT,
+                                VARIANT_LPCALC,
+                                eCSSProperty_row_gap,
+                                eCSSProperty_column_gap);
 }
 
 // normal | [<number> <integer>?]
@@ -11448,6 +11441,33 @@ CSSParserImpl::ParseBoxProperties(const nsCSSPropertyID aPropIDs[])
   return true;
 }
 
+bool
+CSSParserImpl::ParseBoxPairProperties(int32_t aSingleVariantMask,
+                                      int32_t aPairVariantMask,
+                                      nsCSSPropertyID aStart,
+                                      nsCSSPropertyID aEnd)
+{
+  nsCSSValue first;
+  if (ParseSingleTokenVariant(first, aSingleVariantMask, nullptr)) {
+    AppendValue(aStart, first);
+    AppendValue(aEnd, first);
+    return true;
+  }
+  if (ParseNonNegativeVariant(first, aPairVariantMask, nullptr) !=
+        CSSParseResult::Ok) {
+    return false;
+  }
+  nsCSSValue second;
+  auto result = ParseNonNegativeVariant(second, aPairVariantMask, nullptr);
+  if (result == CSSParseResult::Error) {
+    return false;
+  }
+  AppendValue(aStart, first);
+  AppendValue(aEnd,
+              result == CSSParseResult::NotFound ? first : second);
+  return true;
+}
+
 // Similar to ParseBoxProperties, except there is only one property
 // with the result as its value, not four.
 bool
@@ -12045,6 +12065,10 @@ CSSParserImpl::ParsePropertyByFunction(nsCSSPropertyID aPropID)
     return ParseListStyle();
   case eCSSProperty_margin:
     return ParseMargin();
+  case eCSSProperty_margin_block:
+    return ParseMarginBlock();
+  case eCSSProperty_margin_inline:
+    return ParseMarginInline();
   case eCSSProperty_object_position:
     return ParseObjectPosition();
   case eCSSProperty_outline:
@@ -12053,6 +12077,10 @@ CSSParserImpl::ParsePropertyByFunction(nsCSSPropertyID aPropID)
     return ParseOverflow();
   case eCSSProperty_padding:
     return ParsePadding();
+  case eCSSProperty_padding_block:
+    return ParsePaddingBlock();
+  case eCSSProperty_padding_inline:
+    return ParsePaddingInline();
   case eCSSProperty_quotes:
     return ParseQuotes();
   case eCSSProperty_text_decoration:
@@ -15503,6 +15531,24 @@ CSSParserImpl::ParseMargin()
   return ParseBoxProperties(kMarginSideIDs);
 }
 
+bool
+CSSParserImpl::ParseMarginBlock()
+{
+  return ParseBoxPairProperties(VARIANT_AUTO | VARIANT_INHERIT,
+                                VARIANT_AUTO | VARIANT_LPCALC,
+                                eCSSProperty_margin_block_start,
+                                eCSSProperty_margin_block_end);
+}
+
+bool
+CSSParserImpl::ParseMarginInline()
+{
+  return ParseBoxPairProperties(VARIANT_AUTO | VARIANT_INHERIT,
+                                VARIANT_AUTO | VARIANT_LPCALC,
+                                eCSSProperty_margin_inline_start,
+                                eCSSProperty_margin_inline_end);
+}
+
 bool
 CSSParserImpl::ParseObjectPosition()
 {
@@ -15589,6 +15635,24 @@ CSSParserImpl::ParsePadding()
   return ParseBoxProperties(kPaddingSideIDs);
 }
 
+bool
+CSSParserImpl::ParsePaddingBlock()
+{
+  return ParseBoxPairProperties(VARIANT_AUTO | VARIANT_INHERIT,
+                                VARIANT_AUTO | VARIANT_LPCALC,
+                                eCSSProperty_padding_block_start,
+                                eCSSProperty_padding_block_end);
+}
+
+bool
+CSSParserImpl::ParsePaddingInline()
+{
+  return ParseBoxPairProperties(VARIANT_AUTO | VARIANT_INHERIT,
+                                VARIANT_AUTO | VARIANT_LPCALC,
+                                eCSSProperty_padding_inline_start,
+                                eCSSProperty_padding_inline_end);
+}
+
 bool
 CSSParserImpl::ParseQuotes()
 {
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index f78dd0103c..141e8e3125 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -2494,6 +2494,13 @@ CSS_PROP_SHORTHAND(
         CSS_PROPERTY_UNITLESS_LENGTH_QUIRK |
         CSS_PROPERTY_APPLIES_TO_PAGE_RULE,
     "")
+CSS_PROP_SHORTHAND(
+    margin-block,
+    margin_block,
+    MarginBlock,
+    CSS_PROPERTY_PARSE_FUNCTION |
+        CSS_PROPERTY_APPLIES_TO_PAGE_RULE,
+    "")
 CSS_PROP_LOGICAL(
     margin-block-end,
     margin_block_end,
@@ -2546,6 +2553,13 @@ CSS_PROP_MARGIN(
     nullptr,
     offsetof(nsStyleMargin, mMargin),
     eStyleAnimType_Sides_Bottom)
+CSS_PROP_SHORTHAND(
+    margin-inline,
+    margin_inline,
+    MarginInline,
+    CSS_PROPERTY_PARSE_FUNCTION |
+        CSS_PROPERTY_APPLIES_TO_PAGE_RULE,
+    "")
 CSS_PROP_LOGICAL(
     margin-inline-end,
     margin_inline_end,
@@ -3245,6 +3259,12 @@ CSS_PROP_SHORTHAND(
     CSS_PROPERTY_PARSE_FUNCTION |
         CSS_PROPERTY_UNITLESS_LENGTH_QUIRK,
     "")
+CSS_PROP_SHORTHAND(
+    padding-block,
+    padding_block,
+    PaddingBlock,
+    CSS_PROPERTY_PARSE_FUNCTION,
+    "")
 CSS_PROP_LOGICAL(
     padding-block-end,
     padding_block_end,
@@ -3303,6 +3323,12 @@ CSS_PROP_PADDING(
     nullptr,
     offsetof(nsStylePadding, mPadding),
     eStyleAnimType_Sides_Bottom)
+CSS_PROP_SHORTHAND(
+    padding-inline,
+    padding_inline,
+    PaddingInline,
+    CSS_PROPERTY_PARSE_FUNCTION,
+    "")
 CSS_PROP_LOGICAL(
     padding-inline-end,
     padding_inline_end,
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index 0f3a1daeda..7f1fe2c18f 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -2927,6 +2927,17 @@ static const nsCSSPropertyID gMarginSubpropTable[] = {
   eCSSProperty_UNKNOWN
 };
 
+static const nsCSSPropertyID gMarginBlockSubpropTable[] = {
+  eCSSProperty_margin_block_start,
+  eCSSProperty_margin_block_end,
+  eCSSProperty_UNKNOWN
+};
+
+static const nsCSSPropertyID gMarginInlineSubpropTable[] = {
+  eCSSProperty_margin_inline_start,
+  eCSSProperty_margin_inline_end,
+  eCSSProperty_UNKNOWN
+};
 
 static const nsCSSPropertyID gOutlineSubpropTable[] = {
   // nsCSSDeclaration.cpp outputs the subproperties in this order.
@@ -3023,6 +3034,18 @@ static const nsCSSPropertyID gPaddingSubpropTable[] = {
   eCSSProperty_UNKNOWN
 };
 
+static const nsCSSPropertyID gPaddingBlockSubpropTable[] = {
+  eCSSProperty_padding_block_start,
+  eCSSProperty_padding_block_end,
+  eCSSProperty_UNKNOWN
+};
+
+static const nsCSSPropertyID gPaddingInlineSubpropTable[] = {
+  eCSSProperty_padding_inline_start,
+  eCSSProperty_padding_inline_end,
+  eCSSProperty_UNKNOWN
+};
+
 static const nsCSSPropertyID gTextDecorationSubpropTable[] = {
   eCSSProperty_text_decoration_color,
   eCSSProperty_text_decoration_line,
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index 46ef89ba0c..e8ce0190f1 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -1810,6 +1810,22 @@ var gCSSProperties = {
     other_values: [ "rect(3px 20px 15px 4px)", "rect(17px, 21px, 33px, 2px)" ],
     invalid_values: [ "rect(17px, 21px, 33, 2px)" ]
   },
+  "margin-inline": {
+    domProp: "marginInline",
+    inherited: false,
+    type: CSS_TYPE_TRUE_SHORTHAND,
+    subproperties: [ "margin-inline-start", "margin-inline-end" ],
+    initial_values: [ "0", "0px 0em" ],
+    other_values: [ "1px", "3em 1%", "5%",
+      "calc(2px) 1%",
+      "calc(-2px) 1%",
+      "calc(50%) 1%",
+      "calc(3*25px) calc(2px)",
+      "calc(25px*3) 1em",
+      "calc(3*25px + 50%) calc(3*25px - 50%)",
+    ],
+    invalid_values: [ "5", "..25px", ".+5px", ".px", "-.px", "++5px", "-+4px", "+-3px", "--7px", "+-.6px", "-+.5px", "++.7px", "--.4px" ],
+  },
   "margin-inline-end": {
     domProp: "marginInlineEnd",
     inherited: false,
@@ -1959,6 +1975,22 @@ var gCSSProperties = {
             ],
     invalid_values: [ "-1px", "4px -2px", "inherit 2px", "2px inherit", "2", "2px 2", "2 2px" ]
   },
+  "padding-inline": {
+    domProp: "paddingInline",
+    inherited: false,
+    type: CSS_TYPE_TRUE_SHORTHAND,
+    subproperties: [ "padding-inline-start", "padding-inline-end" ],
+    initial_values: [ "0", "0px 0em" ],
+    other_values: [ "1px", "3em 1%", "5%",
+      "calc(2px) 1%",
+      "calc(-2px) 1%",
+      "calc(50%) 1%",
+      "calc(3*25px) calc(2px)",
+      "calc(25px*3) 1em",
+      "calc(3*25px + 50%) calc(3*25px - 50%)",
+    ],
+    invalid_values: [ "5", "..25px", ".+5px", ".px", "-.px", "++5px", "-+4px", "+-3px", "--7px", "+-.6px", "-+.5px", "++.7px", "--.4px" ],
+  },
   "padding-inline-end": {
     domProp: "paddingInlineEnd",
     inherited: false,
@@ -5269,6 +5301,22 @@ var gCSSProperties = {
     ],
     invalid_values: [ "none" ],
   },
+  "margin-block": {
+    domProp: "marginBlock",
+    inherited: false,
+    type: CSS_TYPE_TRUE_SHORTHAND,
+    subproperties: [ "margin-block-start", "margin-block-end" ],
+    initial_values: [ "0", "0px 0em" ],
+    other_values: [ "1px", "3em 1%", "5%",
+      "calc(2px) 1%",
+      "calc(-2px) 1%",
+      "calc(50%) 1%",
+      "calc(3*25px) calc(2px)",
+      "calc(25px*3) 1em",
+      "calc(3*25px + 50%) calc(3*25px - 50%)",
+    ],
+    invalid_values: [ "5", "..25px", ".+5px", ".px", "-.px", "++5px", "-+4px", "+-3px", "--7px", "+-.6px", "-+.5px", "++.7px", "--.4px" ],
+  },
   "margin-block-end": {
     domProp: "marginBlockEnd",
     inherited: false,
@@ -5531,6 +5579,22 @@ var gCSSProperties = {
     alias_for: "inset-inline-end",
     subproperties: [ "inset-inline-end" ],
   },
+  "padding-block": {
+    domProp: "paddingBlock",
+    inherited: false,
+    type: CSS_TYPE_TRUE_SHORTHAND,
+    subproperties: [ "padding-block-start", "padding-block-end" ],
+    initial_values: [ "0", "0px 0em" ],
+    other_values: [ "1px", "3em 1%", "5%",
+      "calc(2px) 1%",
+      "calc(-2px) 1%",
+      "calc(50%) 1%",
+      "calc(3*25px) calc(2px)",
+      "calc(25px*3) 1em",
+      "calc(3*25px + 50%) calc(3*25px - 50%)",
+    ],
+    invalid_values: [ "5", "..25px", ".+5px", ".px", "-.px", "++5px", "-+4px", "+-3px", "--7px", "+-.6px", "-+.5px", "++.7px", "--.4px" ],
+  },
   "padding-block-end": {
     domProp: "paddingBlockEnd",
     inherited: false,