Refactor to allow usage of getKeyboardEvent in behavior

This change consists of some minor refactoring of
keyboard-shortcut-behavior.html to allow for its use in elements that
have the behavior. Also fixes some incorrect bower paths that resulted
in flaky and/or failing tests.

Bug: Issue 5109, Issue 6217
Change-Id: I3a73036b2e34372fe1bf4de836e11bb88b1d0e5f

polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html

@@ -20,24 +20,24 @@ limitations under the License.
 (function(window) {
   'use strict';
 
+  // Must be declared outside behavior implementation to be accessed inside
+  // behavior functions.
   const getKeyboardEvent = function(e) {
-    return Polymer.dom(e.detail ? e.detail.keyboardEvent : e);
+    e = Polymer.dom(e.detail ? e.detail.keyboardEvent : e);
+    // When e is a keyboardEvent, e.event is not null.
+    if (e.event) { e = e.event; }
+    return e;
   };
 
   /** @polymerBehavior KeyboardShortcutBehaviorImpl */
   const KeyboardShortcutBehaviorImpl = {
     modifierPressed(e) {
       e = getKeyboardEvent(e);
-      // When e is a keyboardEvent, e.event is not null.
-      if (e.event) { e = e.event; }
       return e.altKey || e.ctrlKey || e.metaKey || e.shiftKey;
     },
 
     isModifierPressed(e, modifier) {
-      e = getKeyboardEvent(e);
-      // When e is a keyboardEvent, e.event is not null.
-      if (e.event) { e = e.event; }
-      return e[modifier];
+      return getKeyboardEvent(e)[modifier];
     },
 
     shouldSuppressKeyboardShortcut(e) {
@@ -50,6 +50,11 @@ limitations under the License.
       }
       return false;
     },
+
+    // Alias for getKeyboardEvent.
+    getKeyboardEvent(e) {
+      return getKeyboardEvent(e);
+    },
   };
 
   window.Gerrit = window.Gerrit || {};