Gerrit: Fixup gr-message to support anon user (ie a user with no name)

It was showing the user with no name. So users that don't have an
avatar would be invisible. Use a fallback name like we do with the
account dropdown.
See https://gerrit-review.googlesource.com/c/111815/?polygerrit=1

Change-Id: I853d450718e7bd7a9b1555a0c93740a0beea2447

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

diff --git a/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.html b/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.html
index 4fc12b5..85db3a1 100644
--- a/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.html
+++ b/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.html
@@ -14,6 +14,7 @@
 limitations under the License.
 -->
 
+<link rel="import" href="../../../behaviors/gr-anonymous-name-behavior/gr-anonymous-name-behavior.html">
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
 <link rel="import" href="../../shared/gr-button/gr-button.html">
 <link rel="import" href="../../shared/gr-dropdown/gr-dropdown.html">
@@ -40,7 +41,7 @@
         items=[[links]]
         top-content=[[topContent]]
         horizontal-align="right">
-        <span hidden$="[[_hasAvatars]]" hidden>[[_accountName(account, _anonymousName)]]</span>
+        <span hidden$="[[_hasAvatars]]" hidden>[[_accountName(account)]]</span>
         <gr-avatar account="[[account]]" hidden$="[[!_hasAvatars]]" hidden
             image-size="56" aria-label="Account avatar"></gr-avatar>
     </gr-dropdown>