Fix listening on ENTER shortcut in <gr-file-list>

ENTER on buttons should be ignored from global shortcuts. For example
in the file list ENTER should normally open the currently selected file,
but not when the user focus in on the "SAVE" button for a comment.

Google-Bug-Id: b/207642158
Change-Id: Ie20f8ba065e16722f1a8b0e7682f105d200c1020
(cherry picked from commit d98ad48027640b653709fb23519eaf8d9326c733)
diff --git a/polygerrit-ui/app/utils/dom-util.ts b/polygerrit-ui/app/utils/dom-util.ts
index e2fa8fe..dd408d3 100644
--- a/polygerrit-ui/app/utils/dom-util.ts
+++ b/polygerrit-ui/app/utils/dom-util.ts
@@ -452,7 +452,10 @@
     // Suppress shortcuts if the key is 'enter'
     // and target is an anchor or button or paper-tab.
     (e.keyCode === 13 &&
-      (tagName === 'A' || tagName === 'BUTTON' || tagName === 'PAPER-TAB'))
+      (tagName === 'A' ||
+        tagName === 'BUTTON' ||
+        tagName === 'GR-BUTTON' ||
+        tagName === 'PAPER-TAB'))
   ) {
     return true;
   }
diff --git a/polygerrit-ui/app/utils/dom-util_test.ts b/polygerrit-ui/app/utils/dom-util_test.ts
index 9dd5be2..5429550 100644
--- a/polygerrit-ui/app/utils/dom-util_test.ts
+++ b/polygerrit-ui/app/utils/dom-util_test.ts
@@ -320,6 +320,15 @@
       });
     });
 
+    test('suppress "enter" shortcut event from <gr-button>', async () => {
+      await keyEventOn(
+        document.createElement('gr-button'),
+        e => assert.isTrue(shouldSuppress(e)),
+        13,
+        'enter'
+      );
+    });
+
     test('suppress "enter" shortcut event from <a>', async () => {
       await keyEventOn(document.createElement('a'), e => {
         assert.isFalse(shouldSuppress(e));