Resetting frame focus to top-level frame on refresh

The W3C WebDriver Specification dictates that issuing the Refresh command
will reset the focus to the top-level frame. This commit brings the IE
driver into compliance with that part of the spec.

Author: jimevans

cpp/iedriver/CommandHandlers/RefreshCommandHandler.cpp

@@ -38,6 +38,7 @@ namespace webdriver {
       return;
     }
     status_code = browser_wrapper->Refresh();
+    browser_wrapper->SetFocusedFrameByElement(NULL);
     response->SetSuccessResponse(Json::Value::null);
   }