Oilpan: fix build after r201639.

TBR=oilpan-reviews
BUG=none
NOTRY=true

Review URL: https://codereview.chromium.org/1312073003

git-svn-id: svn://svn.chromium.org/blink/trunk@201650 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/css/ElementRuleCollector.h

@@ -62,7 +62,11 @@ public:
     }
 
 private:
-    RawPtrWillBeMember<const RuleData> m_ruleData;
+    // FIXME: Oilpan: RuleData is in the oilpan heap and this pointer
+    // really should be traced. However, RuleData objects are
+    // allocated inside larger TerminatedArray objects and we cannot
+    // trace a raw rule data pointer at this point.
+    const RuleData* m_ruleData;
     unsigned m_specificity;
     uint64_t m_position;
     RawPtrWillBeMember<const CSSStyleSheet> m_parentStyleSheet;