Oilpan: make SuspendableScriptExecutor safe.

Source/web/SuspendableScriptExecutor.cpp

Index: Source/web/SuspendableScriptExecutor.cpp
diff --git a/Source/web/SuspendableScriptExecutor.cpp b/Source/web/SuspendableScriptExecutor.cpp
index e4c95204d52448eacffdd18898ec0959bce89fa5..03459c6a33b858e7a74a1e5944ac0ba5ff88cf81 100644
--- a/Source/web/SuspendableScriptExecutor.cpp
+++ b/Source/web/SuspendableScriptExecutor.cpp
@@ -28,7 +28,7 @@ void SuspendableScriptExecutor::contextDestroyed()
     // and context remained suspend (method resume has never called)
     SuspendableTimer::contextDestroyed();
     m_callback->completed(Vector<v8::Local<v8::Value>>());
-    deref();
+    dispose();
 }
 
 SuspendableScriptExecutor::SuspendableScriptExecutor(LocalFrame* frame, int worldID, const WillBeHeapVector<ScriptSourceCode>& sources, int extensionGroup, bool userGesture, WebScriptExecutionCallback* callback)
@@ -81,6 +81,15 @@ void SuspendableScriptExecutor::executeAndDestroySelf()
         results.append(scriptValue);
     }
     m_callback->completed(results);
+    dispose();
+}
+
+void SuspendableScriptExecutor::dispose()
+{
+#if ENABLE(OILPAN)
+    // Remove object as a ContextLifecycleObserver.
+    ActiveDOMObject::clearContext();

[haraken, 2015/06/23 09:25:56]

Is this a performance optimization? Or do we need to explicitly remove the
observer for correctness?

(It seems a bit strange to call clearContext in contextDestroyed.)

[sof, 2015/06/23 09:40:59]

I think it makes sense to remove oneself here, rather than keep a weak reference
lingering. We know this observer's lifetime is up.

[haraken, 2015/06/23 09:44:55]

Makes sense. (I'd prefer calling ActiveDOMObject::clearContext() only in
executeAndDestroySelf() though; it's up to you.)

+#endif
     deref();
 }