Revert of Streamline frame detach

Source/core/frame/Frame.h

Index: Source/core/frame/Frame.h
diff --git a/Source/core/frame/Frame.h b/Source/core/frame/Frame.h
index c31bb006cb5e11a44e05b4907f4fbf20c0ec29ae..4de75697368724a9d39588a167b869f3e4d3a1c7 100644
--- a/Source/core/frame/Frame.h
+++ b/Source/core/frame/Frame.h
@@ -59,10 +59,11 @@
     virtual void trace(Visitor*);
 
     virtual void navigate(Document& originDocument, const KURL&, const Referrer&, bool lockBackForwardList) = 0;
-    virtual void detach();
+    virtual void detach() = 0;
     void detachChildren();
 
     FrameClient* client() const;
+    void clearClient();
 
     // NOTE: Page is moving out of Blink up into the browser process as
     // part of the site-isolation (out of process iframes) work.
@@ -120,6 +121,11 @@
     return m_client;
 }
 
+inline void Frame::clearClient()
+{
+    m_client = 0;
+}
+
 inline LocalDOMWindow* Frame::domWindow() const
 {
     return m_domWindow.get();