Update Polymer from 1.2.1 -> 1.2.3

third_party/polymer/v1_0/components-chromium/iron-input/README.md

-# iron-input
 
-An input with data binding.
+<!---
+
+This README is automatically generated from the comments in these files:
+iron-input.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-input.svg?branch=master)](https://travis-ci.org/PolymerElements/iron-input)
+
+_[Demo and API Docs](https://elements.polymer-project.org/elements/iron-input)_
+
+
+##&lt;iron-input&gt;
+
+
+`<iron-input>` adds two-way binding and custom validators using `Polymer.IronValidatorBehavior`
+to `<input>`.
+
+### Two-way binding
 
 By default you can only get notified of changes to an `input`'s `value` due to user input:
 
-```html
-<input value="{{myValue::input}}">
-```
+    <input value="{{myValue::input}}">
 
 `iron-input` adds the `bind-value` property that mirrors the `value` property, and can be used
 for two-way data binding. `bind-value` will notify if it is changed either by user input or by script.
 
-```html
-<input is="iron-input" bind-value="{{myValue}}">
-```
+    <input is="iron-input" bind-value="{{myValue}}">
+
+### Custom validators
+
+You can use custom validators that implement `Polymer.IronValidatorBehavior` with `<iron-input>`.
+
+    <input is="iron-input" validator="my-custom-validator">
+
+### Stopping invalid input
+
+It may be desirable to only allow users to enter certain characters. You can use the
+`prevent-invalid-input` and `allowed-pattern` attributes together to accomplish this. This feature
+is separate from validation, and `allowed-pattern` does not affect how the input is validated.
+
+    <!-- only allow characters that match [0-9] -->
+    <input is="iron-input" prevent-invalid-input allowed-pattern="[0-9]">
+
+