Change on-tap to on-click for iron-dropdown

This fixes an issue under iOS 13 when clicking a button in the dropdown
would not work.

Bug: Issue 11984
Change-Id: I339524e1c9cde49f74c2b5228ca35ec9c0dfdece
(cherry picked from commit ed757c0e7a)

polygerrit-ui/app/elements/shared/gr-dropdown-list/gr-dropdown-list.html

@@ -147,7 +147,7 @@ limitations under the License.
         id="dropdown"
         vertical-align="top"
         allow-outside-scroll="true"
-        on-tap="_handleDropdownTap">
+        on-click="_handleDropdownClick">
       <paper-listbox
           class="dropdown-content"
           slot="dropdown-content"

polygerrit-ui/app/elements/shared/gr-dropdown-list/gr-dropdown-list.js

@@ -75,7 +75,7 @@
      * Handle a click on the iron-dropdown element.
      * @param {!Event} e
      */
-    _handleDropdownTap(e) {
+    _handleDropdownClick(e) {
       // async is needed so that that the click event is fired before the
       // dropdown closes (This was a bug for touch devices).
       this.async(() => {

polygerrit-ui/app/elements/shared/gr-dropdown/gr-dropdown.html

@@ -109,7 +109,7 @@ limitations under the License.
         vertical-offset="[[verticalOffset]]"
         allow-outside-scroll="true"
         horizontal-align="[[horizontalAlign]]"
-        on-tap="_handleDropdownTap">
+        on-click="_handleDropdownClick">
       <div class="dropdown-content" slot="dropdown-content">
         <ul>
           <template is="dom-if" if="[[topContent]]">

polygerrit-ui/app/elements/shared/gr-dropdown/gr-dropdown.js

@@ -152,7 +152,7 @@
      * Handle a click on the iron-dropdown element.
      * @param {!Event} e
      */
-    _handleDropdownTap(e) {
+    _handleDropdownClick(e) {
       this._close();
     },