Make mergeable check more explicit

The 'mergeable' property of a change exists only if it is specifically
asked for, otherwise it is undefined. This was causing some false
positives when checking for merge conflicts.

Also removes some dead code.

Bug: Issue 6819
Change-Id: Ib42bac8067afacb09d20cd122f9d9f41425207e0

polygerrit-ui/app/behaviors/rest-client-behavior/rest-client-behavior.html

@@ -122,7 +122,8 @@ limitations under the License.
         states.push('Merged');
       } else if (change.status === this.ChangeStatus.ABANDONED) {
         states.push('Abandoned');
-      } else if (!change.mergeable) {
+      } else if (change.mergeable === false) {
+        // 'mergeable' prop may not always exist (@see Issue 6819)
         states.push('Merge Conflict');
       }
       if (change.work_in_progress) { states.push('WIP'); }

polygerrit-ui/app/behaviors/rest-client-behavior/rest-client-behavior_test.html

@@ -100,11 +100,26 @@ limitations under the License.
         current_revision: 'rev1',
         status: 'NEW',
         labels: {},
+        mergeable: false,
       };
       const status = element.changeStatusString(change);
       assert.equal(status, 'Merge Conflict');
     });
 
+    test('mergeable prop undefined', () => {
+      const change = {
+        change_id: 'Iad9dc96274af6946f3632be53b106ef80f7ba6ca',
+        revisions: {
+          rev1: {_number: 1},
+        },
+        current_revision: 'rev1',
+        status: 'NEW',
+        labels: {},
+      };
+      const status = element.changeStatusString(change);
+      assert.equal(status, '');
+    });
+
     test('Merged status', () => {
       const change = {
         change_id: 'Iad9dc96274af6946f3632be53b106ef80f7ba6ca',

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

@@ -623,10 +623,6 @@
       return Gerrit.Nav.getUrlForChange(change);
     },
 
-    _privateChanges(change) {
-      return change.is_private ? ' (Private)' : '';
-    },
-
     _computeShowCommitInfo(changeStatus, current_revision) {
       return changeStatus === 'Merged' && current_revision;
     },