Remove background change on hover/active in gr-dropdown

+ Also remove redundant gr-button within gr-account-dropdown.

Change-Id: I5cb4020355289b48be98fa74150092009f07544b

polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.html

@@ -36,11 +36,9 @@ limitations under the License.
     </style>
     <gr-dropdown items=[[links]] top-content=[[topContent]]
         horizontal-align="right">
-      <gr-button link class="dropdown-trigger" id="trigger">
         <span hidden$="[[_hasAvatars]]" hidden>[[account.name]]</span>
         <gr-avatar account="[[account]]" hidden$="[[!_hasAvatars]]" hidden
             image-size="56"></gr-avatar>
-      </gr-button>
     </gr-dropdown>
     <gr-rest-api-interface id="restAPI"></gr-rest-api-interface>
   </template>

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

@@ -46,6 +46,11 @@ limitations under the License.
       gr-button[link] {
         padding: 1em 0;
       }
+      gr-button:focus:not([primary]):not([secondary]),
+      gr-button:hover:not([primary]):not([secondary]) {
+        background-color: transparent;
+        border-color: transparent;
+      }
       ul {
         list-style: none;
       }