Handle LocalFrame being nestedly detached by subframe.

Source/core/frame/LocalFrame.cpp

Index: Source/core/frame/LocalFrame.cpp
diff --git a/Source/core/frame/LocalFrame.cpp b/Source/core/frame/LocalFrame.cpp
index 837b38ac87116e94034b5d2e352d1f74c51ad0f4..35975f313b488a5891afda26cba9c194895d7d12 100644
--- a/Source/core/frame/LocalFrame.cpp
+++ b/Source/core/frame/LocalFrame.cpp
@@ -281,6 +281,11 @@ void LocalFrame::detach(FrameDetachType type)
     m_loader.stopAllLoaders();
     m_loader.dispatchUnloadEvent();
     detachChildren();
+
+    // All done if detaching the subframes brought about a detach of this frame also.
+    if (!client())
+        return;
+
     // stopAllLoaders() needs to be called after detachChildren(), because detachChildren()
     // will trigger the unload event handlers of any child frames, and those event
     // handlers might start a new subresource load in this frame.