Add a separate call to initialize the bounds for a sky <iframe> element.

sky/engine/core/loader/EmptyClients.h

Index: sky/engine/core/loader/EmptyClients.h
diff --git a/sky/engine/core/loader/EmptyClients.h b/sky/engine/core/loader/EmptyClients.h
index e0e9945b31ca0f5513fc08e782812cbb94f192be..2130dffc2e8faaa16743db3068eea903fbea59df 100644
--- a/sky/engine/core/loader/EmptyClients.h
+++ b/sky/engine/core/loader/EmptyClients.h
@@ -129,7 +129,7 @@ public:
     virtual void didStopLoading() override { }
 
     virtual void loadURLExternally(const ResourceRequest&, NavigationPolicy, const String& = String()) override { }
-    virtual void createView(const KURL&) override {}
+    virtual mojo::View* createChildFrame(const KURL&) override { return nullptr; }
 
     virtual void transitionToCommittedForNewPage() override { }