Make CSSParserContext be garbage collected.

third_party/WebKit/Source/core/inspector/InspectorCSSAgent.cpp

Index: third_party/WebKit/Source/core/inspector/InspectorCSSAgent.cpp
diff --git a/third_party/WebKit/Source/core/inspector/InspectorCSSAgent.cpp b/third_party/WebKit/Source/core/inspector/InspectorCSSAgent.cpp
index 4a33eb8f9fd3c3681f191a87f324661d38987007..dbceeaa1f9a3dd1456cef86367e456801adc3ebc 100644
--- a/third_party/WebKit/Source/core/inspector/InspectorCSSAgent.cpp
+++ b/third_party/WebKit/Source/core/inspector/InspectorCSSAgent.cpp
@@ -110,8 +110,8 @@ String createShorthandValue(Document* document,
   StyleSheetContents* styleSheetContents =
       StyleSheetContents::create(strictCSSParserContext());
   String text = " div { " + shorthand + ": " + oldText + "; }";
-  CSSParser::parseSheet(CSSParserContext(*document, nullptr),
-                        styleSheetContents, text);
+  CSSParser::parseSheet(new CSSParserContext(*document), styleSheetContents,
+                        text);
 
   CSSStyleSheet* styleSheet = CSSStyleSheet::create(styleSheetContents);
   CSSStyleRule* rule = toCSSStyleRule(styleSheet->item(0));