Fix inline diff expansion and reviewed state

Previously, expanding an inline diff toggled the reviewed state for that
file. This is wrong -- expanding the diff should just mark the file as
reviewed, not unreviewed.

Change-Id: I5533a3f286fbd2db2b9437f4cbf4fa546d347304
diff --git a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
index c1eb39c..83f1565 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
+++ b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
@@ -431,17 +431,21 @@
       return GrCountStringFormatter.computeShortString(commentCount, 'c');
     },
 
-    _reviewFile(path) {
+    /**
+     * @param {string} path
+     * @param {boolean=} opt_reviewed
+     */
+    _reviewFile(path, opt_reviewed) {
       if (this.editMode) { return; }
       const index = this._files.findIndex(file => file.__path === path);
-      const reviewed = this._files[index].isReviewed;
+      const reviewed = opt_reviewed || !this._files[index].isReviewed;
 
-      this.set(['_files', index, 'isReviewed'], !reviewed);
+      this.set(['_files', index, 'isReviewed'], reviewed);
       if (index < this._shownFiles.length) {
-        this.set(['_shownFiles', index, 'isReviewed'], !reviewed);
+        this.set(['_shownFiles', index, 'isReviewed'], reviewed);
       }
 
-      this._saveReviewedState(path, !reviewed);
+      this._saveReviewedState(path, reviewed);
     },
 
     _saveReviewedState(path, reviewed) {
@@ -961,7 +965,7 @@
               path, this.patchRange, this.projectConfig);
           const promises = [diffElem.reload()];
           if (this._loggedIn && !this.diffPrefs.manual_review) {
-            promises.push(this._reviewFile(path));
+            promises.push(this._reviewFile(path, true));
           }
           return Promise.all(promises);
         }).then(() => {
diff --git a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html
index 0e0a39e..ca31943 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html
+++ b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list_test.html
@@ -1036,6 +1036,7 @@
         delete element.diffPrefs.manual_review;
         return element._renderInOrder(['p'], diffs, 1).then(() => {
           assert.isTrue(reviewStub.called);
+          assert.isTrue(reviewStub.calledWithExactly('p', true));
         });
       });
     });