Revert of Detach old frame on WebFrame::swap.

Source/core/loader/FrameLoader.h

Index: Source/core/loader/FrameLoader.h
diff --git a/Source/core/loader/FrameLoader.h b/Source/core/loader/FrameLoader.h
index 1aae7db2ff17f2c00bdd134a6d2e6ae384321d12..82b5b1d0fa8418561dc01d8e46e09650b1bee5db 100644
--- a/Source/core/loader/FrameLoader.h
+++ b/Source/core/loader/FrameLoader.h
@@ -156,11 +156,6 @@
     void finishedParsing();
     void checkCompleted();
 
-    // This prepares the FrameLoader for the next commit. It will dispatch
-    // unload events, abort XHR requests and detach the document. Returns true
-    // if the frame is ready to receive the next commit, or false otherwise.
-    bool prepareForCommit();
-
     void commitProvisionalLoad();
 
     FrameLoaderStateMachine* stateMachine() const { return &m_stateMachine; }