Fix usage of property '_projectConfig'

- gr-change-view: access with wrong name
- gr-diff-view: missing property declaration

Change-Id: I6751e16d80698fa86029d93a45ee54fc5a7b9b5d

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

@@ -279,7 +279,7 @@ limitations under the License.
           comments="[[_comments]]"
           drafts="[[_diffDrafts]]"
           revisions="[[_change.revisions]]"
-          projectConfig="[[projectConfig]]"
+          projectConfig="[[_projectConfig]]"
           selected-index="{{viewState.selectedFileIndex}}"></gr-file-list>
       <gr-messages-list id="messageList"
           change-num="[[_changeNum]]"

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

@@ -69,6 +69,7 @@
         value: true,
       },
       _prefs: Object,
+      _projectConfig: Object,
       _userPrefs: Object,
       _diffMode: {
         type: String,