Workaround for 'polymer-cli lint' bug

The 'polymer-cli lint' is a replacement for the deprecated polylint
tool. The polymer-cli tool has a known bug - it breaks when there is an
empty style block - https://github.com/Polymer/tools/issues/408. A
workaround is to add some comment inside empty style block.

Change-Id: Iec82362ec9e72ae5aeff92f352992333b461a5cf
diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.html b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
index da5eb39..fbd5d68d 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.html
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
@@ -31,7 +31,9 @@
 
 <dom-module id="gr-message">
   <template>
-    <style include="gr-voting-styles"></style>
+    <style include="gr-voting-styles">
+      /* Workaround for empty style block - see https://github.com/Polymer/tools/issues/408 */
+    </style>
     <style include="shared-styles">
       :host {
         border-bottom: 1px solid var(--border-color);