Make consistent avatars in change log

Change gr-account-chip to gr-account-link in change log updates
(Added to cc:, etc). It will make consistent with avatars in first
column of change log. Also gr-account-chip contains remove button,
since it is used in reviewer/ccs list and gr-account-link without
this button has smaller DOM subtree, so we will have smaller number
of DOM elements rendered. On the average change page
it saved 200 elements (2% of all elements).

Change-Id: I547302f398c586be63f3183b1482c61decf86125
diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message_html.js b/polygerrit-ui/app/elements/change/gr-message/gr-message_html.js
index 94b293b..21535d6 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message_html.js
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message_html.js
@@ -280,7 +280,7 @@
                 items="[[update.reviewers]]"
                 as="reviewer"
               >
-                <gr-account-chip account="[[reviewer]]"> </gr-account-chip>
+                <gr-account-link account="[[reviewer]]"> </gr-account-link>
               </template>
             </div>
           </template>