Merge changes I8d335dd6,Ibb519fac

* changes:
  Remove legacy-data-mixin
  Remove _legacyUndefinedCheck from the samples modules

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

@@ -27,7 +27,6 @@ limitations under the License.
 <link rel="import" href="/bower_components/polymer/polymer.html">
 <link rel="import" href="/bower_components/polymer-resin/standalone/polymer-resin.html">
 <!-- TODO(taoalpha): Remove once all legacyUndefinedCheck removed. -->
-<link rel="import" href="/bower_components/polymer/lib/legacy/legacy-data-mixin.html">
 <link rel="import" href="../behaviors/safe-types-behavior/safe-types-behavior.html">
 <script>
   security.polymer_resin.install({

polygerrit-ui/app/samples/bind-parameters.html

@@ -15,7 +15,7 @@
   <script>
     Polymer({
       is: 'my-bind-sample',
-      _legacyUndefinedCheck: true,
+
       properties: {
         computedExample: {
           type: String,

polygerrit-ui/app/samples/repo-command.html

@@ -29,7 +29,7 @@
   <script>
     Polymer({
       is: 'repo-command-low',
-      _legacyUndefinedCheck: true,
+
       attached() {
         console.log(this.repoName);
         console.log(this.config);

polygerrit-ui/app/samples/some-screen.html

@@ -38,7 +38,7 @@
   <script>
     Polymer({
       is: 'some-screen-main',
-      _legacyUndefinedCheck: true,
+
       properties: {
         rootUrl: String,
       },

polygerrit-ui/app/test/common-test-setup.html

@@ -62,6 +62,5 @@ limitations under the License.
 </script>
 <link rel="import"
     href="/bower_components/iron-test-helpers/iron-test-helpers.html" />
-<link rel="import" href="/bower_components/polymer/lib/legacy/legacy-data-mixin.html">
 <link rel="import" href="test-router.html" />
 <script src="/bower_components/moment/moment.js"></script>