Update polymer to 1.11.2 (#797)

Author: Georgehe4

bower.json

@@ -17,7 +17,7 @@
     "tests"
   ],
   "dependencies": {
-    "polymer": "Polymer/polymer#~1.0.2",
+    "polymer": "Polymer/polymer#~1.11.2",
     "iron-flex-layout": "PolymerElements/iron-flex-layout#^1.0.0",
     "iron-icon": "PolymerElements/iron-icon#^1.0.0",
     "iron-icons": "PolymerElements/iron-icons#^1.0.0",

pubspec.lock

@@ -471,4 +471,4 @@ packages:
     source: hosted
     version: "2.1.12"
 sdks:
-  dart: ">=1.23.0 <=2.0.0-dev.16.0"
+  dart: ">=1.23.0 <=2.0.0-dev.23.0"