Make CSSValuePool thread local to ensure correct parsing in colors on workers

third_party/WebKit/Source/web/WebCSSParser.cpp

Index: third_party/WebKit/Source/web/WebCSSParser.cpp
diff --git a/third_party/WebKit/Source/web/WebCSSParser.cpp b/third_party/WebKit/Source/web/WebCSSParser.cpp
index 9082507340c77d21f184994792b5c625daf06ab5..0bc4c0cf9cb8ce73319b8dc56f75108d147d6dfd 100644
--- a/third_party/WebKit/Source/web/WebCSSParser.cpp
+++ b/third_party/WebKit/Source/web/WebCSSParser.cpp
@@ -12,7 +12,7 @@ namespace blink {
 bool WebCSSParser::parseColor(WebColor* webColor, const WebString& colorString)
 {
     Color color = Color(*webColor);
-    bool success = CSSParser::parseColor(color, colorString, true);
+    bool success = CSSParser::parseColor(color, colorString, nullptr, true);
     *webColor = color.rgb();
     return success;
 }