Remove uses of deprecated toWebCoreStringWithUndefinedOrNullCheck(v8::Handle<v8::Value>)

Source/bindings/v8/custom/V8WindowCustom.cpp

Index: Source/bindings/v8/custom/V8WindowCustom.cpp
diff --git a/Source/bindings/v8/custom/V8WindowCustom.cpp b/Source/bindings/v8/custom/V8WindowCustom.cpp
index 0b67b777cff0adde1db81e8ca78d91544d9ad1e7..8ce5827eb2bb845295a486bca31c976b650f7fd7 100644
--- a/Source/bindings/v8/custom/V8WindowCustom.cpp
+++ b/Source/bindings/v8/custom/V8WindowCustom.cpp
@@ -366,10 +366,9 @@ void V8Window::showModalDialogMethodCustom(const v8::FunctionCallbackInfo<v8::Va
         return;
     }
 
-    // FIXME: Handle exceptions properly.
-    String urlString = toWebCoreStringWithUndefinedOrNullCheck(info[0]);
+    V8TRYCATCH_FOR_V8STRINGRESOURCE_VOID(V8StringResource<WithUndefinedOrNullCheck>, urlString, info[0]);
     DialogHandler handler(info[1]);
-    String dialogFeaturesString = toWebCoreStringWithUndefinedOrNullCheck(info[2]);
+    V8TRYCATCH_FOR_V8STRINGRESOURCE_VOID(V8StringResource<WithUndefinedOrNullCheck>, dialogFeaturesString, info[2]);
 
     impl->showModalDialog(urlString, dialogFeaturesString, activeDOMWindow(), firstDOMWindow(), setUpDialog, &handler);