Roll Polymer to 1.3.1

third_party/polymer/v1_0/components-chromium/iron-flex-layout/iron-flex-layout.html

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 <link rel="import" href="../polymer/polymer.html">
 
 <!--
-The `<iron-flex-layout>` component provides simple ways to use [CSS flexible box layout](https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Flexible_boxes), also known as flexbox. This component provides two different ways to use flexbox:
+The `<iron-flex-layout>` component provides simple ways to use
+[CSS flexible box layout](https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Flexible_boxes),
+also known as flexbox. This component provides two different ways to use flexbox:
 
-1. [Layout classes](https://github.com/PolymerElements/iron-flex-layout/tree/master/classes). The layout class stylesheet provides a simple set of class-based flexbox rules. Layout classes let you specify layout properties directly in markup.
+1. [Layout classes](https://github.com/PolymerElements/iron-flex-layout/tree/master/iron-flex-layout-classes.html).
+The layout class stylesheet provides a simple set of class-based flexbox rules, that
+let you specify layout properties directly in markup. You must include this file
+in every element that needs to use them.
 
-2. [Custom CSS mixins](https://github.com/PolymerElements/iron-flex-layout/blob/master/iron-flex-layout.html). The mixin stylesheet includes custom CSS mixins that can be applied inside a CSS rule using the `@apply` function.
+Sample use:
+
+    <link rel="import" href="../iron-flex-layout/iron-flex-layout-classes.html">
+    <style is="custom-style" include="iron-flex iron-flex-alignment">
+
+    <div class="layout horizontal layout-start">
+      <div>cross axis start alignment</div>
+    </div>
+
+2. [Custom CSS mixins](https://github.com/PolymerElements/iron-flex-layout/blob/master/iron-flex-layout.html).
+The mixin stylesheet includes custom CSS mixins that can be applied inside a CSS rule using the `@apply` function.
+
+Please note that the old [/deep/ layout classes](https://github.com/PolymerElements/iron-flex-layout/tree/master/classes)
+are deprecated, and should not be used. To continue using layout properties
+directly in markup, please switch to using the new `dom-module`-based
+[layout classes](https://github.com/PolymerElements/iron-flex-layout/tree/master/iron-flex-layout-classes.html).
+Please note that the new version does not use `/deep/`, and therefore requires you
+to import the `dom-modules` in every element that needs to use them.
 
 A complete [guide](https://elements.polymer-project.org/guides/flex-layout) to `<iron-flex-layout>` is available.
 
 @group Iron Elements
 @pseudoElement iron-flex-layout
 @demo demo/index.html
 -->
 
 <style>
   /* IE 10 support for HTML5 hidden attr */
@@ skipping 181 matching lines @@
       justify-content: center;
     };
 
     --layout-end-justified: {
       -ms-flex-pack: end;
       -webkit-justify-content: flex-end;
       justify-content: flex-end;
     };
 
     --layout-around-justified: {
-      -ms-flex-pack: around;
+      -ms-flex-pack: distribute;
       -webkit-justify-content: space-around;
       justify-content: space-around;
     };
 
     --layout-justified: {
       -ms-flex-pack: justify;
       -webkit-justify-content: space-between;
       justify-content: space-between;
     };
 
@@ skipping 88 matching lines @@
     --layout-fixed-left: {
       position: fixed;
       top: 0;
       bottom: 0;
       left: 0;
     };
 
   }
 
 </style>