Set key for SelectPluginSheet row

Summary: Getting a React warning because it previously didn't.

Reviewed By: jknoxville

Differential Revision: D17736486

fbshipit-source-id: 422e023abe0501804d5b447e365ff014969d6286

src/chrome/SelectPluginSheet.tsx

@@ -151,6 +151,7 @@ export default class SelectPluginSheet extends Component<Props, State> {
               return (
                 <PluginRowComponent
                   name={pluginID}
+                  key={pluginID}
                   selected={selected}
                   onChange={(id: string, selected: boolean) => {
                     plugins.set(id, selected);