Disallow script execution after unload event dispatch in frame detach.

Source/core/frame/Frame.cpp

Index: Source/core/frame/Frame.cpp
diff --git a/Source/core/frame/Frame.cpp b/Source/core/frame/Frame.cpp
index d45db355c975bbb0c7041fed3c7f2504b8a9c281..56072e83d8c9e3bec9bbaa80407938a9d70eb670 100644
--- a/Source/core/frame/Frame.cpp
+++ b/Source/core/frame/Frame.cpp
@@ -103,12 +103,6 @@ void Frame::trace(Visitor* visitor)
 
 void Frame::detach()
 {
-    // client() should never be null because that means we somehow re-entered
-    // the frame detach code... but it is sometimes.
-    // FIXME: Understand why this is happening so we can document this insanity.
-    // http://crbug.com/371084 is a probable explanation.
-    if (!client())
-        return;

[haraken, 2014/10/16 00:59:27]

Shall we add ASSERT(client())?

[dcheng, 2014/10/16 01:21:32]

Done.

     // After this, we must no longer talk to the client since this clears
     // its owning reference back to our owning LocalFrame.
     m_client->detached();