[third_party] add polymer 1.2.3

polymer_1.2.3/bower_components/iron-collapse/bower.json

 {
   "name": "iron-collapse",
-  "version": "1.0.2",
+  "version": "1.0.5",
   "description": "Provides a collapsable container",
   "authors": [
     "The Polymer Authors"
   ],
   "keywords": [
     "web-components",
     "polymer",
     "container"
   ],
   "private": true,
   "repository": {
     "type": "git",
     "url": "https://github.com/PolymerElements/iron-collapse"
   },
   "license": "http://polymer.github.io/LICENSE.txt",
   "homepage": "https://github.com/PolymerElements/iron-collapse",
   "ignore": [],
   "dependencies": {
     "polymer": "Polymer/polymer#^1.0.0"
   },
   "devDependencies": {
     "web-component-tester": "*",
     "test-fixture": "PolymerElements/test-fixture#^1.0.0",
     "iron-component-page": "PolymerElements/iron-component-page#^1.0.0",
     "paper-styles": "PolymerElements/paper-styles#^1.0.0",
     "webcomponentsjs": "webcomponents/webcomponentsjs#^0.7.0"
-  }
+  },
+  "main": "iron-collapse.html"
 }