Incl. custom properties in CSS property UseCounter

third_party/WebKit/Source/core/frame/UseCounter.cpp

Index: third_party/WebKit/Source/core/frame/UseCounter.cpp
diff --git a/third_party/WebKit/Source/core/frame/UseCounter.cpp b/third_party/WebKit/Source/core/frame/UseCounter.cpp
index 00951c4f95096e49f2e8fcd4ea6e523744ff4917..66330d0baa0a158bab1723ce37ce679f99095b3d 100644
--- a/third_party/WebKit/Source/core/frame/UseCounter.cpp
+++ b/third_party/WebKit/Source/core/frame/UseCounter.cpp
@@ -1239,8 +1239,7 @@ void UseCounter::countCrossOriginIframe(const Document& document,
 }
 
 void UseCounter::count(CSSParserMode cssParserMode, CSSPropertyID property) {
-  // FIXME(suzyh): Count custom properties as well as named properties
-  DCHECK(isCSSPropertyIDWithName(property));
+  DCHECK(isCSSPropertyIDWithName(property) || property == CSSPropertyVariable);
 
   if (!isUseCounterEnabledForMode(cssParserMode) || m_muteCount)
     return;