Fix line wrapping when logged in

+ The property on the diff preferences being used was tab_width
  instead of tab_size so when it was calculating the width of the
  line, a zero-width tab_size was resulting in the visible width
  to be incorrect in all cases.

Change-Id: I815f19fff2bd986fee65c92fde2bfc53596911d8

polygerrit-ui/app/elements/gr-app.html

@@ -212,7 +212,7 @@ limitations under the License.
           // gerrit-extension-api/src/main/jcg/gerrit/extensions/client/DiffPreferencesInfo.java
           this._diffPreferences = {
             context: 10,
-            tab_width: 8,
+            tab_size: 8,
           };
         }
       },

polygerrit-ui/app/elements/gr-diff.html

@@ -95,7 +95,7 @@ limitations under the License.
             path="[[path]]"
             content="{{_diff.leftSide}}"
             width="[[sideWidth]]"
-            tab-width="[[prefs.tab_width]]"
+            tab-width="[[prefs.tab_size]]"
             can-comment="[[_loggedIn]]"
             project-config="[[projectConfig]]"
             on-expand-context="_handleExpandContext"
@@ -108,7 +108,7 @@ limitations under the License.
             path="[[path]]"
             content="{{_diff.rightSide}}"
             width="[[sideWidth]]"
-            tab-width="[[prefs.tab_width]]"
+            tab-width="[[prefs.tab_size]]"
             can-comment="[[_loggedIn]]"
             project-config="[[projectConfig]]"
             on-expand-context="_handleExpandContext"
@@ -797,7 +797,7 @@ limitations under the License.
       _visibleLineLength: function(contents) {
         // http://jsperf.com/performance-of-match-vs-split
         var numTabs = contents.split('\t').length - 1;
-        return contents.length - numTabs + (this.prefs.tab_width * numTabs);
+        return contents.length - numTabs + (this.prefs.tab_size * numTabs);
       },
 
       _maxLinesSpanned: function(left, right) {

polygerrit-ui/app/test/gr-diff-test.html

@@ -44,7 +44,7 @@ limitations under the License.
       element.path = 'sieve.go';
       element.prefs = {
         context: 10,
-        tab_width: 8,
+        tab_size: 8,
       };
 
       server = sinon.fakeServer.create();