Fix hashtag removal

The disabled attribute was attempting to be added on the text rather
than the node, which resulted in a javascript error.

Change-Id: I112624c8f82da719ed6e904a504da3316757c708

polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js

diff --git a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js
index 88b2444..d117d17 100644
--- a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js
+++ b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js
@@ -344,9 +344,10 @@
 
     _handleHashtagRemoved(e) {
       e.preventDefault();
-      const target = Polymer.dom(e).rootTarget.text;
+      const target = Polymer.dom(e).rootTarget;
       target.disabled = true;
-      this.$.restAPI.setChangeHashtag(this.change._number, {remove: [target]})
+      this.$.restAPI.setChangeHashtag(this.change._number,
+          {remove: [target.text]})
           .then(newHashtag => {
             target.disabled = false;
             this.set(['change', 'hashtags'], newHashtag);