Flex the inside of the input control

sky/framework/sky-input.sky

 <!--
 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 -->
 <import src="/sky/framework/sky-element/sky-element.sky" as="SkyElement" />
 
 <sky-element name="sky-input" attributes="value:string">
 <template>
   <style>
   :host {
     display: flex;
     border: 1px solid blue;
     margin: 5px;
     padding: 4px;
   }
   #control {
+    flex: 1;
     align-self: center;
     height: 1.2em;
     white-space: nowrap;
     overflow: hidden;
   }
   </style>
   <div id="control" contenteditable on-keydown="handleKeyDown">{{ value }}</div>
 </template>
 <script>
 module.exports = class extends SkyElement {
@@ skipping 14 matching lines @@
     });
   }
   handleKeyDown(event) {
     // TODO(abarth): You can still get newlines if the user pastes them.
     if (event.keyCode == 0xD)
       event.preventDefault();
   }
 }.register();
 </script>
 </sky-element>