Oilpan: IDBCursor should be detached from IDBRequest when the IDBRequest stops

Source/modules/indexeddb/IDBRequest.cpp

Index: Source/modules/indexeddb/IDBRequest.cpp
diff --git a/Source/modules/indexeddb/IDBRequest.cpp b/Source/modules/indexeddb/IDBRequest.cpp
index 841c81f016cd1fb4bc7f442388695c122eb6fc2b..94027cf65614878befddb15491af0f6ed04106c0 100644
--- a/Source/modules/indexeddb/IDBRequest.cpp
+++ b/Source/modules/indexeddb/IDBRequest.cpp
@@ -369,6 +369,11 @@ bool IDBRequest::hasPendingActivity() const
     return m_hasPendingActivity && !m_contextStopped;
 }
 
+void IDBRequest::contextWillBeDestroyed()
+{
+    checkForReferenceCycle();

[haraken, 2014/04/01 05:56:14]

I need to reconsider what I should do here. Currently this code results in an
infinite loop in some layout tests.

[Mads Ager (chromium), 2014/04/01 11:38:38]

What we want to ensure in this call is that any cursors are detached from the
cursor backend before the dispatcher goes away.

All of these objects for this worker thread are going to die now, so as far as I
can tell, what you need to do here is m_backend.clear() on the IDBCursor object.

That will detach the IDBCursor from the backend while the dispatcher is still
alive. Then we will kill the dispatcher. Then we GC and that will kill these
objects which is now safe since we have detached from the backend before the
dispatcher got killed?

+}
+
 void IDBRequest::stop()
 {
     if (m_contextStopped)