Pull web-animations-js into third-party via the third_party/polymer/reproduce.sh script. Add necess…

third_party/web-animations-js/sources/src/visibility-handler.js

Index: third_party/web-animations-js/sources/src/visibility-handler.js
diff --git a/third_party/web-animations-js/sources/src/visibility-handler.js b/third_party/web-animations-js/sources/src/visibility-handler.js
new file mode 100644
index 0000000000000000000000000000000000000000..53f29535548fda8a1b79fb72d1be02c723b2a3aa
--- /dev/null
+++ b/third_party/web-animations-js/sources/src/visibility-handler.js
@@ -0,0 +1,29 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+// limitations under the License.
+
+(function(scope, testing) {
+
+  function merge(left, right) {
+    if (left != 'visible' && right != 'visible') return;
+    return [0, 1, function(x) {
+      if (x <= 0) return left;
+      if (x >= 1) return right;
+      return 'visible';
+    }];
+  }
+
+  scope.addPropertiesHandler(String, merge, ['visibility']);
+
+})(webAnimations1);
+