Make error messages for cross-domain access OOPIF-friendly.

Source/core/frame/DOMWindow.h

Index: Source/core/frame/DOMWindow.h
diff --git a/Source/core/frame/DOMWindow.h b/Source/core/frame/DOMWindow.h
index 399cec0a49383c2a42a63d2e9c9e0546c48a4dd2..96a8fd58f3db283a9bda67ca02386241581397f4 100644
--- a/Source/core/frame/DOMWindow.h
+++ b/Source/core/frame/DOMWindow.h
@@ -181,11 +181,9 @@ public:
 
     void postMessage(PassRefPtr<SerializedScriptValue> message, const MessagePortArray*, const String& targetOrigin, LocalDOMWindow* source, ExceptionState&);
 
-    // FIXME: These should be non-virtual, but this is blocked on the security
-    // origin replication work.
-    virtual String sanitizedCrossDomainAccessErrorMessage(LocalDOMWindow* callingWindow) = 0;
-    virtual String crossDomainAccessErrorMessage(LocalDOMWindow* callingWindow) = 0;
-    virtual bool isInsecureScriptAccess(DOMWindow& callingWindow, const String& urlString);
+    String sanitizedCrossDomainAccessErrorMessage(LocalDOMWindow* callingWindow);
+    String crossDomainAccessErrorMessage(LocalDOMWindow* callingWindow);
+    bool isInsecureScriptAccess(LocalDOMWindow& callingWindow, const String& urlString);

[alexmos, 2015/04/15 17:15:17]

All of the call sites passed in a LocalDOMWindow, and I don't know why the
callingWindow could be a RemoteDOMWindow, so I changed the signature.  If
there's a good reason to keep it as DOMWindow, please let me know.

Actually, I don't quite understand the point of having this function.  It seems
that all call sites (setLocation, LocalDOMWindow::open, createWindow) call
canNavigate() before calling this.  Do you know what this adds over the security
checks done by canNavigate?

[dcheng, 2015/04/15 21:03:49]

LocalDOMWindow makes more sense.
Are you sure all locations call canNavigate() first? It seems like window.open()
might not, even though it ends up calling this function.

 
     // FIXME: When this DOMWindow is no longer the active DOMWindow (i.e.,
     // when its document is no longer the document that is displayed in its