[third_party] add polymer 1.2.3

polymer_1.2.3/bower_components/iron-page-url/README.md

+
+<!---
+
+This README is automatically generated from the comments in these files:
+iron-page-url.html
+
+Edit those files, and our readme bot will duplicate them over here!
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+-->
+
+[![Build Status](https://travis-ci.org/PolymerElements/iron-page-url.svg?branch=master)](https://travis-ci.org/PolymerElements/iron-page-url)
+
+_[Demo and API Docs](https://elements.polymer-project.org/elements/iron-page-url)_
+
+
+##&lt;iron-page-url&gt;
+
+
+
+The `iron-page-url` element manages binding to and from the current URL.
+
+iron-page-url is the first, and lowest level element in the Polymer team's
+routing system. This is a beta release of iron-page-url as we continue work
+on higher level elements, and as such iron-page-url may undergo breaking
+changes.
+
+#### Properties
+
+When the URL is: `/search?query=583#details` iron-page-url's properties will be:
+
+  - path: `'/search'`
+  - query: `'query=583'`
+  - hash: `'details'`
+
+These bindings are bidirectional. Modifying them will in turn modify the URL.
+
+iron-page-url is only active while it is attached to the document.
+
+#### Links
+
+While iron-page-url is active in the document it will intercept clicks on links
+within your site, updating the URL pushing the updated URL out through the
+databinding system. iron-page-url only intercepts clicks with the intent to
+open in the same window, so middle mouse clicks and ctrl/cmd clicks work fine.
+
+You can customize this behavior with the `urlSpaceRegex`.
+
+#### Dwell Time
+
+iron-page-url protects against accidental history spamming by only adding
+entries to the user's history if the URL stays unchanged for `dwellTime`
+milliseconds.
+
+