Suppress X keyboard shortcut when relevant

Bug: Issue 9357
Change-Id: I3c0e9af93d20f4c85b31d2babd81c5c739e9a1aa

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js

@@ -990,6 +990,7 @@
     },
 
     _handleShiftXKey(e) {
+      if (this.shouldSuppressKeyboardShortcut(e)) { return; }
       this.$.diff.expandAllContext();
     },
   });