Fix a -Wswitch warning in ANGLE.

BUG=505308

Change-Id: I34ae3aa65ce55c4e04eecfef3c9cde9841e47140
Reviewed-on: https://chromium-review.googlesource.com/288245
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Daniel Cheng <dcheng@chromium.org>

util/win32/Win32Window.cpp

@@ -705,6 +705,8 @@ void Win32Window::pushEvent(Event event)
       case Event::EVENT_RESIZED:
         MoveWindow(mNativeWindow, 0, 0, mWidth, mHeight, FALSE);
         break;
+      default:
+        break;
     }
 }