Oilpan: fix build after r183810.

R=haraken
BUG=393913
NOTRY=true

Review URL: https://codereview.chromium.org/662633002

git-svn-id: svn://svn.chromium.org/blink/trunk@183814 bbb929c8-8fbe-4397-9dbb-9b2b20218538
diff --git a/Source/bindings/core/v8/V8Initializer.cpp b/Source/bindings/core/v8/V8Initializer.cpp
index 552f93e..48430fd 100644
--- a/Source/bindings/core/v8/V8Initializer.cpp
+++ b/Source/bindings/core/v8/V8Initializer.cpp
@@ -161,6 +161,7 @@
 namespace {
 
 class PromiseRejectMessage {
+    ALLOW_ONLY_INLINE_ALLOCATION();
 public:
     PromiseRejectMessage(const ScriptValue& promise, PassRefPtrWillBeRawPtr<ScriptCallStack> callStack)
         : m_promise(promise)
@@ -170,6 +171,11 @@
 
     const ScriptValue m_promise;
     const RefPtrWillBeMember<ScriptCallStack> m_callStack;
+
+    void trace(Visitor* visitor)
+    {
+        visitor->trace(m_callStack);
+    }
 };
 
 } // namespace