Fix SelectEventPlugin

mouseup was not fired when context menu showed, so select events stopped being fired.

src/eventPlugins/SelectEventPlugin.js

@@ -192,6 +192,7 @@ var SelectEventPlugin = {
       case topLevelTypes.topMouseDown:
         mouseDown = true;
         break;
+      case topLevelTypes.topContextMenu:
       case topLevelTypes.topMouseUp:
         mouseDown = false;
         return constructSelectEvent(nativeEvent);