Add an attention set icon

As proposed in
https://www.gerritcodereview.com/design-docs/attention-set-solution-1-user-interface.html

Screenshot: https://imgur.com/a/YW0Q1nM

Change-Id: I3bef98f563de1ce0c389ccefeef3523c0eb965b3
diff --git a/polygerrit-ui/app/elements/shared/gr-icons/gr-icons.js b/polygerrit-ui/app/elements/shared/gr-icons/gr-icons.js
index 5d7da6c..f61b1d0 100644
--- a/polygerrit-ui/app/elements/shared/gr-icons/gr-icons.js
+++ b/polygerrit-ui/app/elements/shared/gr-icons/gr-icons.js
@@ -94,51 +94,10 @@
       <g id="review"><path d="M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41z"></path></g>
       <!-- This is a custom PolyGerrit SVG -->
       <g id="zeroState"><path d="M22 9V7h-2V5c0-1.1-.9-2-2-2H4c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h14c1.1 0 2-.9 2-2v-2h2v-2h-2v-2h2v-2h-2V9h2zm-4 10H4V5h14v14zM6 13h5v4H6zm6-6h4v3h-4zM6 7h5v5H6zm6 4h4v6h-4z"></path></g>
+      <!-- This SVG is an adaptation of material.io https://material.io/icons/#label_important-->
+      <g id="attention"><path d="M5.5 19 l9 0 c.67 0 1.27 -.33 1.63 -.84 L20.5 12 l-4.37 -6.16 c-.36 -.51 -.96 -.84 -1.63 -.84 l-9 0 L9 12 z"></path></g>
     </defs>
   </svg>
 </iron-iconset-svg>`;
 
 document.head.appendChild($_documentContainer.content);
-
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from material.io https://material.io/icons/#unfold_more */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/editor-icons.html */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/editor-icons.html */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from material.io https://material.io/icons/#ic_hourglass_full*/
-/* This SVG is a copy from material.io https://material.io/icons/#mode_comment*/
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This SVG is a copy from iron-icons https://github.com/PolymerElements/iron-icons/blob/master/iron-icons.js */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/* This is a custom PolyGerrit SVG */
-/*
-  FIXME(polymer-modulizer): the above comments were extracted
-  from HTML and may be out of place here. Review them and
-  then delete this comment!
-*/
-