Add support for unprefixed CSS Transforms

Source/core/frame/UseCounter.cpp

Index: Source/core/frame/UseCounter.cpp
diff --git a/Source/core/frame/UseCounter.cpp b/Source/core/frame/UseCounter.cpp
index 0d83636b3a4750506cb333622fd03282c8171c52..33d62ee4ee27b6e09ea24d9374f3cc610cd427d7 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -500,6 +500,12 @@ int UseCounter::mapCSSPropertyIdToCSSSampleIdForHistogram(int id)
     case CSSPropertyJustifySelf: return 443;
     case CSSPropertyScrollBehavior: return 444;
     case CSSPropertyWillChange: return 445;
+    case CSSPropertyTransform: return 446;
+    case CSSPropertyTransformOrigin: return 447;
+    case CSSPropertyTransformStyle: return 448;
+    case CSSPropertyPerspective: return 449;
+    case CSSPropertyPerspectiveOrigin: return 450;
+    case CSSPropertyBackfaceVisibility: return 451;
 
     // Add new features above this line (don't change the assigned numbers of the existing
     // items) and update maximumCSSSampleId() with the new maximum value.
@@ -519,7 +525,7 @@ int UseCounter::mapCSSPropertyIdToCSSSampleIdForHistogram(int id)
     return 0;
 }
 
-static int maximumCSSSampleId() { return 445; }
+static int maximumCSSSampleId() { return 451; }
 
 void UseCounter::muteForInspector()
 {