[third_party] add polymer 1.2.3

polymer_1.2.3/iron-ajax/README.md

+
+<!---
+
+This README is automatically generated from the comments in these files:
+iron-ajax.html  iron-request.html
+
+Edit those files, and our readme bot will duplicate them over here!
+Edit this file, and the bot will squash your changes :)
+
+-->
+
+[![Build Status](https://travis-ci.org/PolymerElements/iron-ajax.svg?branch=master)](https://travis-ci.org/PolymerElements/iron-ajax)
+
+_[Demo and API Docs](https://elements.polymer-project.org/elements/iron-ajax)_
+
+
+##&lt;iron-ajax&gt;
+
+
+The `iron-ajax` element exposes network request functionality.
+
+    <iron-ajax
+        auto
+        url="http://gdata.youtube.com/feeds/api/videos/"
+        params='{"alt":"json", "q":"chrome"}'
+        handle-as="json"
+        on-response="handleResponse"
+        debounce-duration="300"></iron-ajax>
+
+With `auto` set to `true`, the element performs a request whenever
+its `url`, `params` or `body` properties are changed. Automatically generated
+requests will be debounced in the case that multiple attributes are changed
+sequentially.
+
+Note: The `params` attribute must be double quoted JSON.
+
+You can trigger a request explicitly by calling `generateRequest` on the
+element.
+
+
+
+##&lt;iron-request&gt;
+
+
+iron-request can be used to perform XMLHttpRequests.
+
+    <iron-request id="xhr"></iron-request>
+    ...
+    this.$.xhr.send({url: url, params: params});
+