Avoid leaking objects between isolated worlds via attribute event listeners

Source/bindings/v8/V8Binding.cpp

Index: Source/bindings/v8/V8Binding.cpp
diff --git a/Source/bindings/v8/V8Binding.cpp b/Source/bindings/v8/V8Binding.cpp
index 9bd2b00b53eb63f053611e22034683d387649fd4..1a6b54c1761c9f6d7a9a9ff5fccb272a0957f5b6 100644
--- a/Source/bindings/v8/V8Binding.cpp
+++ b/Source/bindings/v8/V8Binding.cpp
@@ -433,4 +433,15 @@ WrapperWorldType worldTypeInMainThread(v8::Isolate* isolate)
     return MainWorld;
 }
 
+DOMWrapperWorld* isolatedWorldForIsolate(v8::Isolate* isolate)
+{
+    V8PerIsolateData* data = V8PerIsolateData::from(isolate);
+    if (data->workerDOMDataStore())
+        return 0;
+    if (!DOMWrapperWorld::isolatedWorldsExist())
+        return 0;
+    ASSERT(!v8::Context::GetEntered().IsEmpty());
+    return DOMWrapperWorld::isolatedWorld(v8::Context::GetEntered());
+}
+
 } // namespace WebCore