Bug #24274--> delay creating a dummy channel in DoLoadURL until we are sure

we are going to need it.
r=bienvenu,travis
a=chofmann

docshell/base/nsWebShell.cpp

@@ -1627,9 +1627,11 @@ nsWebShell::DoLoadURL(nsIURI * aUri,
             */
            nsIInterfaceRequestor * interfaceRequestor = NS_STATIC_CAST(nsIInterfaceRequestor *, this);
            nsCOMPtr<nsIChannel> dummyChannel;
+           // creating a channel is expensive...don't create it unless we know we have to
+           // so move the creation down into each of the if clauses...
+           if (nsnull != (const char *) ref) {
               rv = NS_OpenURI(getter_AddRefs(dummyChannel), aUri, nsnull, interfaceRequestor);
               if (NS_FAILED(rv)) return rv;
-           if (nsnull != (const char *) ref) {
               rv = OnStartDocumentLoad(mDocLoader, aUri, "load");
               // Go to the anchor in the current document
               rv = presShell->GoToAnchor(nsAutoString(ref));            
@@ -1645,6 +1647,8 @@ nsWebShell::DoLoadURL(nsIURI * aUri,
            }
            else if (aType == nsISessionHistory::LOAD_HISTORY)
            {
+              rv = NS_OpenURI(getter_AddRefs(dummyChannel), aUri, nsnull, interfaceRequestor);
+              if (NS_FAILED(rv)) return rv;
               rv = OnStartDocumentLoad(mDocLoader, aUri, "load");
               // Go to the top of the current document
               nsCOMPtr<nsIViewManager> viewMgr;

webshell/src/nsWebShell.cpp

@@ -1627,9 +1627,11 @@ nsWebShell::DoLoadURL(nsIURI * aUri,
             */
            nsIInterfaceRequestor * interfaceRequestor = NS_STATIC_CAST(nsIInterfaceRequestor *, this);
            nsCOMPtr<nsIChannel> dummyChannel;
+           // creating a channel is expensive...don't create it unless we know we have to
+           // so move the creation down into each of the if clauses...
+           if (nsnull != (const char *) ref) {
               rv = NS_OpenURI(getter_AddRefs(dummyChannel), aUri, nsnull, interfaceRequestor);
               if (NS_FAILED(rv)) return rv;
-           if (nsnull != (const char *) ref) {
               rv = OnStartDocumentLoad(mDocLoader, aUri, "load");
               // Go to the anchor in the current document
               rv = presShell->GoToAnchor(nsAutoString(ref));            
@@ -1645,6 +1647,8 @@ nsWebShell::DoLoadURL(nsIURI * aUri,
            }
            else if (aType == nsISessionHistory::LOAD_HISTORY)
            {
+              rv = NS_OpenURI(getter_AddRefs(dummyChannel), aUri, nsnull, interfaceRequestor);
+              if (NS_FAILED(rv)) return rv;
               rv = OnStartDocumentLoad(mDocLoader, aUri, "load");
               // Go to the top of the current document
               nsCOMPtr<nsIViewManager> viewMgr;