Issue #1224 - Remove constant expressions from /dom

This excludes DOMProxy handlers in dom bindings because that's intertwined with
codegen and js that needs to be handled together.

34 files changed, 54 insertions, 57 deletions

diff --git a/dom/animation/AnimationPerformanceWarning.h b/dom/animation/AnimationPerformanceWarning.h
index a1ac35cba..582c48cc3 100644
--- a/dom/animation/AnimationPerformanceWarning.h
+++ b/dom/animation/AnimationPerformanceWarning.h
@@ -38,8 +38,6 @@ struct AnimationPerformanceWarning
                               std::initializer_list<int32_t> aParams)
     : mType(aType)
   {
-    // FIXME:  Once std::initializer_list::size() become a constexpr function,
-    // we should use static_assert here.
     MOZ_ASSERT(aParams.size() <= kMaxParamsForLocalization,
       "The length of parameters should be less than "
       "kMaxParamsForLocalization");
@@ -49,11 +47,11 @@ struct AnimationPerformanceWarning
   // Maximum number of parameters passed to
   // nsContentUtils::FormatLocalizedString to localize warning messages.
   //
-  // NOTE: This constexpr can't be forward declared, so if you want to use
+  // NOTE: This can't be forward declared, so if you want to use
   // this variable, please include this header file directly.
   // This value is the same as the limit of nsStringBundle::FormatString.
   // See the implementation of nsStringBundle::FormatString.
-  static constexpr uint8_t kMaxParamsForLocalization = 10;
+  static const uint8_t kMaxParamsForLocalization = 10;
 
   // Indicates why this property could not be animated on the compositor.
   Type mType;
diff --git a/dom/base/WindowNamedPropertiesHandler.h b/dom/base/WindowNamedPropertiesHandler.h
index 227d8c946..cafeadb85 100644
--- a/dom/base/WindowNamedPropertiesHandler.h
+++ b/dom/base/WindowNamedPropertiesHandler.h
@@ -15,7 +15,7 @@ namespace dom {
 class WindowNamedPropertiesHandler : public BaseDOMProxyHandler
 {
 public:
-  constexpr WindowNamedPropertiesHandler()
+  WindowNamedPropertiesHandler()
     : BaseDOMProxyHandler(nullptr, /* hasPrototype = */ true)
   {
   }
diff --git a/dom/base/nsAttrValue.h b/dom/base/nsAttrValue.h
index 23f61a614..33ee91afd 100644
--- a/dom/base/nsAttrValue.h
+++ b/dom/base/nsAttrValue.h
@@ -268,7 +268,7 @@ public:
     // EnumTable can be initialized either with an int16_t value
     // or a value of an enumeration type that can fit within an int16_t.
 
-    constexpr EnumTable(const char* aTag, int16_t aValue)
+    EnumTable(const char* aTag, int16_t aValue)
       : tag(aTag)
       , value(aValue)
     {
@@ -276,7 +276,7 @@ public:
 
     template<typename T,
              typename = typename std::enable_if<std::is_enum<T>::value>::type>
-    constexpr EnumTable(const char* aTag, T aValue)
+    EnumTable(const char* aTag, T aValue)
       : tag(aTag)
       , value(static_cast<int16_t>(aValue))
     {
diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index acd596a44..642681d91 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -956,7 +956,7 @@ NS_IMPL_CYCLE_COLLECTING_RELEASE(DialogValueHolder)
 class nsOuterWindowProxy : public js::Wrapper
 {
 public:
-  constexpr nsOuterWindowProxy() : js::Wrapper(0) { }
+  nsOuterWindowProxy() : js::Wrapper(0) { }
 
   virtual bool finalizeInBackground(const JS::Value& priv) const override {
     return false;
@@ -1407,7 +1407,7 @@ nsOuterWindowProxy::singleton;
 class nsChromeOuterWindowProxy : public nsOuterWindowProxy
 {
 public:
-  constexpr nsChromeOuterWindowProxy() : nsOuterWindowProxy() { }
+  nsChromeOuterWindowProxy() : nsOuterWindowProxy() { }
 
   virtual const char *className(JSContext *cx, JS::Handle<JSObject*> wrapper) const override;
 
diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp
index 605b1917f..0411bee80 100644
--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -1161,7 +1161,7 @@ TimeUntilNow(TimeStamp start)
 
 struct CycleCollectorStats
 {
-  constexpr CycleCollectorStats() :
+  CycleCollectorStats() :
     mMaxGCDuration(0), mRanSyncForgetSkippable(false), mSuspected(0),
     mMaxSkippableDuration(0), mMaxSliceTime(0), mMaxSliceTimeSinceClear(0),
     mTotalSliceTime(0), mAnyLockedOut(false), mExtraForgetSkippableCalls(0),
diff --git a/dom/bindings/BindingUtils.h b/dom/bindings/BindingUtils.h
index 356d3aa00..e97f29359 100644
--- a/dom/bindings/BindingUtils.h
+++ b/dom/bindings/BindingUtils.h
@@ -3073,21 +3073,21 @@ class GetCCParticipant
 {
   // Helper for GetCCParticipant for classes that participate in CC.
   template<class U>
-  static constexpr nsCycleCollectionParticipant*
+  static nsCycleCollectionParticipant*
   GetHelper(int, typename U::NS_CYCLE_COLLECTION_INNERCLASS* dummy=nullptr)
   {
     return T::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant();
   }
   // Helper for GetCCParticipant for classes that don't participate in CC.
   template<class U>
-  static constexpr nsCycleCollectionParticipant*
+  static nsCycleCollectionParticipant*
   GetHelper(double)
   {
     return nullptr;
   }
 
 public:
-  static constexpr nsCycleCollectionParticipant*
+  static nsCycleCollectionParticipant*
   Get()
   {
     // Passing int() here will try to call the GetHelper that takes an int as
@@ -3102,7 +3102,7 @@ template<class T>
 class GetCCParticipant<T, true>
 {
 public:
-  static constexpr nsCycleCollectionParticipant*
+  static nsCycleCollectionParticipant*
   Get()
   {
     return nullptr;
@@ -3125,7 +3125,7 @@ EnumerateGlobal(JSContext* aCx, JS::Handle<JSObject*> aObj);
 template <class T>
 struct CreateGlobalOptions
 {
-  static constexpr ProtoAndIfaceCache::Kind ProtoAndIfaceCacheKind =
+  static const ProtoAndIfaceCache::Kind ProtoAndIfaceCacheKind =
     ProtoAndIfaceCache::NonWindowLike;
   static void TraceGlobal(JSTracer* aTrc, JSObject* aObj)
   {
@@ -3142,7 +3142,7 @@ struct CreateGlobalOptions
 template <>
 struct CreateGlobalOptions<nsGlobalWindow>
 {
-  static constexpr ProtoAndIfaceCache::Kind ProtoAndIfaceCacheKind =
+  static const ProtoAndIfaceCache::Kind ProtoAndIfaceCacheKind =
     ProtoAndIfaceCache::WindowLike;
   static void TraceGlobal(JSTracer* aTrc, JSObject* aObj);
   static bool PostCreateGlobal(JSContext* aCx, JS::Handle<JSObject*> aGlobal);
diff --git a/dom/bindings/DOMJSClass.h b/dom/bindings/DOMJSClass.h
index 6e779840f..c97cf9322 100644
--- a/dom/bindings/DOMJSClass.h
+++ b/dom/bindings/DOMJSClass.h
@@ -210,7 +210,7 @@ struct NativePropertiesN {
 
   const int32_t iteratorAliasMethodIndex;
 
-  constexpr const NativePropertiesN<7>* Upcast() const {
+  const NativePropertiesN<7>* Upcast() const {
     return reinterpret_cast<const NativePropertiesN<7>*>(this);
   }
 
diff --git a/dom/bindings/ErrorResult.h b/dom/bindings/ErrorResult.h
index da7ec30e7..15cf2aa03 100644
--- a/dom/bindings/ErrorResult.h
+++ b/dom/bindings/ErrorResult.h
@@ -56,7 +56,7 @@ enum ErrNum {
 
 // Debug-only compile-time table of the number of arguments of each error, for use in static_assert.
 #if defined(DEBUG) && (defined(__clang__) || defined(__GNUC__))
-uint16_t constexpr ErrorFormatNumArgs[] = {
+uint16_t ErrorFormatNumArgs[] = {
 #define MSG_DEF(_name, _argc, _exn, _str) \
   _argc,
 #include "mozilla/dom/Errors.msg"
diff --git a/dom/cache/DBSchema.cpp b/dom/cache/DBSchema.cpp
index 176e7b9d1..37510e2e1 100644
--- a/dom/cache/DBSchema.cpp
+++ b/dom/cache/DBSchema.cpp
@@ -2460,7 +2460,7 @@ Validate(mozIStorageConnection* aConn)
 typedef nsresult (*MigrationFunc)(mozIStorageConnection*, bool&);
 struct Migration
 {
-  constexpr Migration(int32_t aFromVersion, MigrationFunc aFunc)
+  Migration(int32_t aFromVersion, MigrationFunc aFunc)
     : mFromVersion(aFromVersion)
     , mFunc(aFunc)
   { }
diff --git a/dom/events/EventStates.h b/dom/events/EventStates.h
index 3397110ba..f23ae9873 100644
--- a/dom/events/EventStates.h
+++ b/dom/events/EventStates.h
@@ -27,7 +27,7 @@ public:
   typedef uint64_t InternalType;
   typedef uint8_t ServoType;
 
-  constexpr EventStates()
+  EventStates()
     : mStates(0)
   {
   }
@@ -37,12 +37,12 @@ public:
   // In that case, we could be sure that only macros at the end were creating
   // EventStates instances with mStates set to something else than 0.
   // Unfortunately, this constructor is needed at at least two places now.
-  explicit constexpr EventStates(InternalType aStates)
+  explicit EventStates(InternalType aStates)
     : mStates(aStates)
   {
   }
 
-  EventStates constexpr operator|(const EventStates& aEventStates) const
+  EventStates operator|(const EventStates& aEventStates) const
   {
     return EventStates(mStates | aEventStates.mStates);
   }
@@ -56,7 +56,7 @@ public:
   // NOTE: calling if (eventStates1 & eventStates2) will not build.
   // This might work correctly if operator bool() is defined
   // but using HasState, HasAllStates or HasAtLeastOneOfStates is recommended.
-  EventStates constexpr operator&(const EventStates& aEventStates) const
+  EventStates operator&(const EventStates& aEventStates) const
   {
     return EventStates(mStates & aEventStates.mStates);
   }
diff --git a/dom/heapsnapshot/HeapSnapshot.cpp b/dom/heapsnapshot/HeapSnapshot.cpp
index 299a96a9c..668b7f5a5 100644
--- a/dom/heapsnapshot/HeapSnapshot.cpp
+++ b/dom/heapsnapshot/HeapSnapshot.cpp
@@ -1455,7 +1455,7 @@ HeapSnapshot::CreateUniqueCoreDumpFile(ErrorResult& rv,
 class DeleteHeapSnapshotTempFileHelperChild
 {
 public:
-  constexpr DeleteHeapSnapshotTempFileHelperChild() { }
+  DeleteHeapSnapshotTempFileHelperChild() { }
 
   void operator()(PHeapSnapshotTempFileHelperChild* ptr) const {
     Unused << NS_WARN_IF(!HeapSnapshotTempFileHelperChild::Send__delete__(ptr));
diff --git a/dom/html/HTMLInputElement.cpp b/dom/html/HTMLInputElement.cpp
index f2c14ff2d..a1ffbb15d 100644
--- a/dom/html/HTMLInputElement.cpp
+++ b/dom/html/HTMLInputElement.cpp
@@ -5858,8 +5858,6 @@ HTMLInputElement::ParseAttribute(int32_t aNamespaceID,
                                  const nsAString& aValue,
                                  nsAttrValue& aResult)
 {
-  // We can't make these static_asserts because kInputDefaultType and
-  // kInputTypeTable aren't constexpr.
   MOZ_ASSERT(kInputDefaultType->value == NS_FORM_INPUT_TEXT,
              "Someone forgot to update kInputDefaultType when adding a new "
              "input type.");
diff --git a/dom/html/HTMLTrackElement.cpp b/dom/html/HTMLTrackElement.cpp
index 758018f8d..59810a444 100644
--- a/dom/html/HTMLTrackElement.cpp
+++ b/dom/html/HTMLTrackElement.cpp
@@ -57,7 +57,7 @@ namespace mozilla {
 namespace dom {
 
 // Map html attribute string values to TextTrackKind enums.
-static constexpr nsAttrValue::EnumTable kKindTable[] = {
+static nsAttrValue::EnumTable kKindTable[] = {
   { "subtitles", static_cast<int16_t>(TextTrackKind::Subtitles) },
   { "captions", static_cast<int16_t>(TextTrackKind::Captions) },
   { "descriptions", static_cast<int16_t>(TextTrackKind::Descriptions) },
@@ -68,7 +68,7 @@ static constexpr nsAttrValue::EnumTable kKindTable[] = {
 
 // Invalid values are treated as "metadata" in ParseAttribute, but if no value
 // at all is specified, it's treated as "subtitles" in GetKind
-static constexpr const nsAttrValue::EnumTable* kKindTableInvalidValueDefault = &kKindTable[4];
+static const nsAttrValue::EnumTable* kKindTableInvalidValueDefault = &kKindTable[4];
 
 class WindowDestroyObserver final : public nsIObserver
 {
diff --git a/dom/indexedDB/ActorsParent.cpp b/dom/indexedDB/ActorsParent.cpp
index 74afef452..c7feb8d86 100644
--- a/dom/indexedDB/ActorsParent.cpp
+++ b/dom/indexedDB/ActorsParent.cpp
@@ -270,7 +270,7 @@ const uint32_t kDEBUGTransactionThreadSleepMS = 0;
 #endif
 
 template <size_t N>
-constexpr size_t
+size_t
 LiteralStringLength(const char (&aArr)[N])
 {
   static_assert(N, "Zero-length string literal?!");
@@ -2905,11 +2905,11 @@ UpgradeKeyFunction::CopyAndUpgradeKeyBufferInternal(const uint8_t*& aSource,
   MOZ_ASSERT(aDestination);
   MOZ_ASSERT(aTagOffset <=  Key::kMaxArrayCollapse);
 
-  static constexpr uint8_t kOldNumberTag = 0x1;
-  static constexpr uint8_t kOldDateTag = 0x2;
-  static constexpr uint8_t kOldStringTag = 0x3;
-  static constexpr uint8_t kOldArrayTag = 0x4;
-  static constexpr uint8_t kOldMaxType = kOldArrayTag;
+  static uint8_t kOldNumberTag = 0x1;
+  static uint8_t kOldDateTag = 0x2;
+  static uint8_t kOldStringTag = 0x3;
+  static uint8_t kOldArrayTag = 0x4;
+  static uint8_t kOldMaxType = kOldArrayTag;
 
   if (NS_WARN_IF(aRecursionDepth > Key::kMaxRecursionDepth)) {
     IDB_REPORT_INTERNAL_ERR();
diff --git a/dom/media/MediaCache.cpp b/dom/media/MediaCache.cpp
index 37399f851..64523afcb 100644
--- a/dom/media/MediaCache.cpp
+++ b/dom/media/MediaCache.cpp
@@ -277,7 +277,7 @@ protected:
   };
 
   struct BlockOwner {
-    constexpr BlockOwner() {}
+    BlockOwner() {}
 
     // The stream that owns this block, or null if the block is free.
     MediaCacheStream* mStream = nullptr;
diff --git a/dom/media/platforms/PDMFactory.h b/dom/media/platforms/PDMFactory.h
index 2b43fa1ab..a13c99ac0 100644
--- a/dom/media/platforms/PDMFactory.h
+++ b/dom/media/platforms/PDMFactory.h
@@ -49,10 +49,10 @@ public:
   void SetCDMProxy(CDMProxy* aProxy);
 #endif
 
-  static constexpr int kYUV400 = 0;
-  static constexpr int kYUV420 = 1;
-  static constexpr int kYUV422 = 2;
-  static constexpr int kYUV444 = 3;
+  static const int kYUV400 = 0;
+  static const int kYUV420 = 1;
+  static const int kYUV422 = 2;
+  static const int kYUV444 = 3;
 
 private:
   virtual ~PDMFactory();
diff --git a/dom/smil/SMILBoolType.h b/dom/smil/SMILBoolType.h
index 608a09ccf..d0bbcf5ea 100644
--- a/dom/smil/SMILBoolType.h
+++ b/dom/smil/SMILBoolType.h
@@ -42,7 +42,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SMILBoolType() {}
+  SMILBoolType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/smil/SMILEnumType.h b/dom/smil/SMILEnumType.h
index b6cda3ff9..070ae60bb 100644
--- a/dom/smil/SMILEnumType.h
+++ b/dom/smil/SMILEnumType.h
@@ -43,7 +43,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SMILEnumType() {}
+  SMILEnumType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/smil/SMILIntegerType.h b/dom/smil/SMILIntegerType.h
index 39560cc79..bf8030b6e 100644
--- a/dom/smil/SMILIntegerType.h
+++ b/dom/smil/SMILIntegerType.h
@@ -38,7 +38,8 @@ public:
   }
 
 private:
-  constexpr SMILIntegerType() {}
+  // Private constructor: prevent instances beyond my singleton.
+  SMILIntegerType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/smil/SMILStringType.h b/dom/smil/SMILStringType.h
index 6f160cadb..6fb51b7d9 100644
--- a/dom/smil/SMILStringType.h
+++ b/dom/smil/SMILStringType.h
@@ -43,7 +43,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SMILStringType() {}
+  SMILStringType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/smil/nsSMILCSSValueType.h b/dom/smil/nsSMILCSSValueType.h
index 0c71605f0..0303e69e3 100644
--- a/dom/smil/nsSMILCSSValueType.h
+++ b/dom/smil/nsSMILCSSValueType.h
@@ -110,7 +110,7 @@ public:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr nsSMILCSSValueType() {}
+  nsSMILCSSValueType() {}
 };
 
 #endif // NS_SMILCSSVALUETYPE_H_
diff --git a/dom/smil/nsSMILFloatType.h b/dom/smil/nsSMILFloatType.h
index fd57e4a77..470e935d3 100644
--- a/dom/smil/nsSMILFloatType.h
+++ b/dom/smil/nsSMILFloatType.h
@@ -41,7 +41,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr nsSMILFloatType() {}
+  nsSMILFloatType() {}
 };
 
 #endif // NS_SMILFLOATTYPE_H_
diff --git a/dom/smil/nsSMILNullType.h b/dom/smil/nsSMILNullType.h
index d21610ff4..c668773ce 100644
--- a/dom/smil/nsSMILNullType.h
+++ b/dom/smil/nsSMILNullType.h
@@ -44,7 +44,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr nsSMILNullType() {}
+  nsSMILNullType() {}
 };
 
 #endif // NS_SMILNULLTYPE_H_
diff --git a/dom/svg/SVGIntegerPairSMILType.h b/dom/svg/SVGIntegerPairSMILType.h
index 52af5d3dc..ae62781fd 100644
--- a/dom/svg/SVGIntegerPairSMILType.h
+++ b/dom/svg/SVGIntegerPairSMILType.h
@@ -45,7 +45,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGIntegerPairSMILType() {}
+  SVGIntegerPairSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/svg/SVGLengthListSMILType.h b/dom/svg/SVGLengthListSMILType.h
index 10321b585..2fbb84488 100644
--- a/dom/svg/SVGLengthListSMILType.h
+++ b/dom/svg/SVGLengthListSMILType.h
@@ -93,7 +93,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGLengthListSMILType() {}
+  SVGLengthListSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/svg/SVGMotionSMILType.h b/dom/svg/SVGMotionSMILType.h
index 7529d796d..768c90093 100644
--- a/dom/svg/SVGMotionSMILType.h
+++ b/dom/svg/SVGMotionSMILType.h
@@ -78,7 +78,7 @@ public:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGMotionSMILType() {}
+  SVGMotionSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/svg/SVGNumberListSMILType.h b/dom/svg/SVGNumberListSMILType.h
index 5e8db8afe..efdabdb14 100644
--- a/dom/svg/SVGNumberListSMILType.h
+++ b/dom/svg/SVGNumberListSMILType.h
@@ -47,7 +47,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGNumberListSMILType() {}
+  SVGNumberListSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/svg/SVGNumberPairSMILType.h b/dom/svg/SVGNumberPairSMILType.h
index 0f90163f5..a88a0f5ac 100644
--- a/dom/svg/SVGNumberPairSMILType.h
+++ b/dom/svg/SVGNumberPairSMILType.h
@@ -40,7 +40,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGNumberPairSMILType() {}
+  SVGNumberPairSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/svg/SVGOrientSMILType.h b/dom/svg/SVGOrientSMILType.h
index 6b30cbee0..904b37680 100644
--- a/dom/svg/SVGOrientSMILType.h
+++ b/dom/svg/SVGOrientSMILType.h
@@ -60,7 +60,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGOrientSMILType() {}
+  SVGOrientSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/svg/SVGPathSegListSMILType.h b/dom/svg/SVGPathSegListSMILType.h
index 6856ef275..5e4e89141 100644
--- a/dom/svg/SVGPathSegListSMILType.h
+++ b/dom/svg/SVGPathSegListSMILType.h
@@ -51,7 +51,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGPathSegListSMILType() {}
+  SVGPathSegListSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/svg/SVGPointListSMILType.h b/dom/svg/SVGPointListSMILType.h
index 6f58bd42e..053959553 100644
--- a/dom/svg/SVGPointListSMILType.h
+++ b/dom/svg/SVGPointListSMILType.h
@@ -47,7 +47,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGPointListSMILType() {}
+  SVGPointListSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/svg/SVGTransformListSMILType.h b/dom/svg/SVGTransformListSMILType.h
index 526f9ba50..6572815a1 100644
--- a/dom/svg/SVGTransformListSMILType.h
+++ b/dom/svg/SVGTransformListSMILType.h
@@ -123,7 +123,7 @@ public:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGTransformListSMILType() {}
+  SVGTransformListSMILType() {}
 };
 
 } // end namespace mozilla
diff --git a/dom/svg/SVGViewBoxSMILType.h b/dom/svg/SVGViewBoxSMILType.h
index f05f3928d..54b171263 100644
--- a/dom/svg/SVGViewBoxSMILType.h
+++ b/dom/svg/SVGViewBoxSMILType.h
@@ -40,7 +40,7 @@ protected:
 
 private:
   // Private constructor: prevent instances beyond my singleton.
-  constexpr SVGViewBoxSMILType() {}
+  SVGViewBoxSMILType() {}
 };
 
 } // namespace mozilla
diff --git a/dom/xbl/nsXBLMaybeCompiled.h b/dom/xbl/nsXBLMaybeCompiled.h
index d4b366b0e..ba66ec5d5 100644
--- a/dom/xbl/nsXBLMaybeCompiled.h
+++ b/dom/xbl/nsXBLMaybeCompiled.h
@@ -124,7 +124,7 @@ struct BarrierMethods<nsXBLMaybeCompiled<UncompiledT>>
 template <class T>
 struct IsHeapConstructibleType<nsXBLMaybeCompiled<T>>
 { // Yes, this is the exception to the rule. Sorry.
-  static constexpr bool value = true;
+  static const bool value = true;
 };
 
 template <class UncompiledT>