Make WebFrame::isLoading() local-only and map it to load event completion

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 4105569918b64d59cdffd3ef0f2c559dba4e988d..cd59b852947c6df7ad1f5833790a1878161746eb 100644
--- a/Source/core/loader/FrameLoader.h
+++ b/Source/core/loader/FrameLoader.h
@@ -114,8 +114,6 @@ public:
     // waiting to notify would allow a URL spoof.
     void notifyIfInitialDocumentAccessed();
 
-    bool isLoading() const;
-
     DocumentLoader* documentLoader() const { return m_documentLoader.get(); }
     DocumentLoader* policyDocumentLoader() const { return m_policyDocumentLoader.get(); }
     DocumentLoader* provisionalDocumentLoader() const { return m_provisionalDocumentLoader.get(); }