--- a/layout/style/Declaration.cpp
+++ b/layout/style/Declaration.cpp
@@ -407,31 +407,16 @@ Declaration::GetImageLayerValue(
       const nsCSSProps::KTableEntry* clipTable = nsCSSProps::kKeywordTableTable[aTable[nsStyleImageLayers::clip]];
       for (size_t i = 0; originTable[i].mValue != -1; i++) {
         // For each keyword & value in kOriginKTable, ensure that
         // kBackgroundKTable has a matching entry at the same position.
         MOZ_ASSERT(originTable[i].mKeyword == clipTable[i].mKeyword);
         MOZ_ASSERT(originTable[i].mValue == clipTable[i].mValue);
       }
 #endif
-      static_assert(static_cast<uint8_t>(StyleGeometryBox::Content) ==
-                    static_cast<uint8_t>(StyleImageLayerOrigin::Content) &&
-                    static_cast<uint8_t>(StyleGeometryBox::Padding) ==
-                    static_cast<uint8_t>(StyleImageLayerOrigin::Padding) &&
-                    static_cast<uint8_t>(StyleGeometryBox::Border) ==
-                    static_cast<uint8_t>(StyleImageLayerOrigin::Border) &&
-                    static_cast<uint8_t>(StyleGeometryBox::Margin) ==
-                    static_cast<uint8_t>(StyleImageLayerOrigin::Margin) &&
-                    static_cast<uint8_t>(StyleGeometryBox::Fill) ==
-                    static_cast<uint8_t>(StyleImageLayerOrigin::Fill) &&
-                    static_cast<uint8_t>(StyleGeometryBox::Stroke) ==
-                    static_cast<uint8_t>(StyleImageLayerOrigin::Stroke) &&
-                    static_cast<uint8_t>(StyleGeometryBox::View) ==
-                    static_cast<uint8_t>(StyleImageLayerOrigin::View),
-                    "bg-clip and bg-origin style constants must agree");
       aValue.Append(char16_t(' '));
       origin->mValue.AppendToString(aTable[nsStyleImageLayers::origin], aValue,
                                     aSerialization);
 
       if (clip->mValue != origin->mValue) {
         aValue.Append(char16_t(' '));
         clip->mValue.AppendToString(aTable[nsStyleImageLayers::clip], aValue,
                                     aSerialization);

--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -12450,31 +12450,16 @@ CSSParserImpl::ParseImageLayersItem(
         const KTableEntry* clipTable = nsCSSProps::kKeywordTableTable[aTable[nsStyleImageLayers::clip]];
         for (size_t i = 0; originTable[i].mValue != -1; i++) {
           // For each keyword & value in kOriginKTable, ensure that
           // kBackgroundKTable has a matching entry at the same position.
           MOZ_ASSERT(originTable[i].mKeyword == clipTable[i].mKeyword);
           MOZ_ASSERT(originTable[i].mValue == clipTable[i].mValue);
         }
 #endif
-        static_assert(static_cast<uint8_t>(StyleGeometryBox::Content) ==
-                      static_cast<uint8_t>(StyleImageLayerOrigin::Content) &&
-                      static_cast<uint8_t>(StyleGeometryBox::Padding) ==
-                      static_cast<uint8_t>(StyleImageLayerOrigin::Padding) &&
-                      static_cast<uint8_t>(StyleGeometryBox::Border) ==
-                      static_cast<uint8_t>(StyleImageLayerOrigin::Border) &&
-                      static_cast<uint8_t>(StyleGeometryBox::Margin) ==
-                      static_cast<uint8_t>(StyleImageLayerOrigin::Margin) &&
-                      static_cast<uint8_t>(StyleGeometryBox::Fill) ==
-                      static_cast<uint8_t>(StyleImageLayerOrigin::Fill) &&
-                      static_cast<uint8_t>(StyleGeometryBox::Stroke) ==
-                      static_cast<uint8_t>(StyleImageLayerOrigin::Stroke) &&
-                      static_cast<uint8_t>(StyleGeometryBox::View) ==
-                      static_cast<uint8_t>(StyleImageLayerOrigin::View),
-                      "bg-clip and bg-origin style constants must agree");
 
         CSSParseResult result =
           ParseSingleValueProperty(aState.mClip->mValue,
                                    aTable[nsStyleImageLayers::clip]);
         MOZ_ASSERT(result != CSSParseResult::Error,
                    "how can failing to parse a single background-clip value "
                    "consume tokens?");
         if (result == CSSParseResult::NotFound) {