Enhance special filename sorting

Previously, filenames were directly locale compared, which caused some
instances of sorting to occur incorrectly (e.g. sorting task.go after
task_test.go). The new behavior is to compare the filenames first, and
then compare the filename with extension iff the filenames are equal.

Bug: Issue 4545
Change-Id: I9fe5a5b111c8ae9b4dc587b97753aa6aa11224ef

polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.js

@@ -139,8 +139,8 @@
       } else {
         target.blur();
       }
-      // @see Issue 4255.
       if (this._inputVal) {
+        // @see Issue 4255.
         page.show('/q/' +
             encodeURIComponent(encodeURIComponent(this._inputVal)));
       }

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js

@@ -442,8 +442,7 @@
           return 1;
         }
       }
-
-      return a.localeCompare(b);
+      return aFile.localeCompare(bFile) || a.localeCompare(b);
     },
 
     getChangeRevisionActions: function(changeNum, patchNum) {

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface_test.html

@@ -252,6 +252,17 @@ limitations under the License.
             'minidump/minidump_thread_writer.h',
             'minidump/minidump_thread_writer.cc',
           ]);
+
+      // Regression test for Issue 4545.
+      assert.deepEqual([
+          'task_test.go',
+          'task.go',
+          ]
+        .sort(element._specialFilePathCompare),
+          [
+            'task.go',
+            'task_test.go',
+          ]);
     });
 
     test('rebase always enabled', function(done) {