fix l10n of stopButton

fix #4548

Auditors: @bsclifton

Test Plan:
1. Go to "https://upload.wikimedia.org/wikipedia/commons/d/d9/Der_Kaufmann_Georg_Gisze_%28Hans_Holbein_the_Younger%29.jpg"
2. Hover over the stop loading 'x'

Author: darkdh

js/components/navigationBar.js

@@ -118,7 +118,7 @@ class NavigationBar extends ImmutableComponent {
           ? <span className='browserButton' />
           : this.loading
             ? <Button iconClass='fa-times'
-              l10nId='reloadButton'
+              l10nId='stopButton'
               className='navbutton stop-button'
               onClick={this.onStop} />
             : <Button iconClass='fa-repeat'