Make CSSParserContext be garbage collected.

third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.cpp

Index: third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.cpp
diff --git a/third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.cpp b/third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.cpp
index 521f6f186aa2f3c26ad9361236fe753a0480e1ed..dc27eab0f37db61e41d1e8803660209ae5502ad1 100644
--- a/third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.cpp
+++ b/third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.cpp
@@ -400,9 +400,8 @@ void BaseRenderingContext2D::setFilter(const String& filterString) {
   if (filterString == state().unparsedFilter())
     return;
 
-  const CSSValue* filterValue =
-      CSSParser::parseSingleValue(CSSPropertyFilter, filterString,
-                                  CSSParserContext(HTMLStandardMode, nullptr));
+  const CSSValue* filterValue = CSSParser::parseSingleValue(
+      CSSPropertyFilter, filterString, new CSSParserContext(HTMLStandardMode));
 
   if (!filterValue || filterValue->isInitialValue() ||
       filterValue->isInheritedValue())