Move StyleSheetResourceClient to Oilpan heap

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

Index: third_party/WebKit/Source/core/css/StyleRuleImport.h
diff --git a/third_party/WebKit/Source/core/css/StyleRuleImport.h b/third_party/WebKit/Source/core/css/StyleRuleImport.h
index 64cad61a54aee655c1336b7ee4eb924252bf582b..88db5857644394049cb4e3f242c29bf9181f3f76 100644
--- a/third_party/WebKit/Source/core/css/StyleRuleImport.h
+++ b/third_party/WebKit/Source/core/css/StyleRuleImport.h
@@ -58,6 +58,7 @@ private:
     // NOTE: We put the StyleSheetResourceClient in a member instead of inheriting from it
     // to avoid adding a vptr to StyleRuleImport.
     class ImportedStyleSheetClient final : public GarbageCollectedFinalized<ImportedStyleSheetClient>, public StyleSheetResourceClient {
+        USING_GARBAGE_COLLECTED_MIXIN(ImportedStyleSheetClient);
     public:
         ImportedStyleSheetClient(StyleRuleImport* ownerRule) : m_ownerRule(ownerRule) { }
         ~ImportedStyleSheetClient() override { }
@@ -70,6 +71,7 @@ private:
         DEFINE_INLINE_TRACE()
         {
             visitor->trace(m_ownerRule);
+            StyleSheetResourceClient::trace(visitor);
         }
 
     private: