Use data-... attributes instead of name property

gr-button doesn't have name property. It is better to use data-...
attributes to attach additional data to the gr-button element.

Change-Id: I33cc62f2e426376db40b3060be91401361da0d90
diff --git a/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.html b/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.html
index b62764b..46fd227 100644
--- a/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.html
+++ b/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.html
@@ -111,7 +111,7 @@
         </template>
         <iron-selector
             id="labelSelector"
-            attr-for-selected="value"
+            attr-for-selected="data-value"
             selected="[[_computeLabelValue(labels, permittedLabels, label)]]"
             hidden$="[[!_computeAnyPermittedLabelValues(permittedLabels, label.name)]]"
             on-selected-item-changed="_setSelectedValueText">
@@ -121,8 +121,8 @@
             <gr-button
                 class$="[[_computeButtonClass(value, index, _items.length)]]"
                 has-tooltip
-                name="[[label.name]]"
-                value$="[[value]]"
+                data-name$="[[label.name]]"
+                data-value$="[[value]]"
                 title$="[[_computeLabelValueTitle(labels, label.name, value)]]">
               [[value]]</gr-button>
           </template>
diff --git a/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.js b/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.js
index 76e6e64..bd7fff8 100644
--- a/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.js
+++ b/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row.js
@@ -140,8 +140,8 @@
       this._selectedValueText = e.target.selectedItem.getAttribute('title');
       // Needed to update the style of the selected button.
       this.updateStyles();
-      const name = e.target.selectedItem.name;
-      const value = e.target.selectedItem.getAttribute('value');
+      const name = e.target.selectedItem.dataset.name;
+      const value = e.target.selectedItem.dataset.value;
       this.dispatchEvent(new CustomEvent(
           'labels-changed',
           {detail: {name, value}, bubbles: true, composed: true}));
diff --git a/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row_test.html b/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row_test.html
index 519fbb8..f1a009a 100644
--- a/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row_test.html
+++ b/polygerrit-ui/app/elements/change/gr-label-score-row/gr-label-score-row_test.html
@@ -110,7 +110,7 @@
       element.addEventListener('labels-changed', labelsChangedHandler);
       assert.ok(element.$.labelSelector);
       MockInteractions.tap(element.$$(
-          'gr-button[value="-1"]'));
+          'gr-button[data-value="-1"]'));
       flushAsynchronousOperations();
       assert.strictEqual(element.selectedValue, '-1');
       assert.strictEqual(element.selectedItem
@@ -167,7 +167,7 @@
 
     test('do not display tooltips on touch devices', () => {
       const verifiedBtn = element.$$(
-          'iron-selector > gr-button[value="-1"]');
+          'iron-selector > gr-button[data-value="-1"]');
 
       // On touch devices, tooltips should not be shown.
       verifiedBtn._isTouchDevice = true;
diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog-it_test.html b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog-it_test.html
index 3632348..a65f76c 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog-it_test.html
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog-it_test.html
@@ -156,7 +156,7 @@
             const labelScoreRows = Polymer.dom(element.$.labelScores.root)
                 .querySelector('gr-label-score-row[name="Code-Review"]');
             const selectedBtn = Polymer.dom(labelScoreRows.root)
-                .querySelector('gr-button[value="+1"].iron-selected');
+                .querySelector('gr-button[data-value="+1"].iron-selected');
             assert.isOk(selectedBtn);
             done();
           });