update core-field metadata

Author: frankiefu

metadata.html

@@ -1,14 +1,17 @@
-<x-meta id="core-field" label="Polymer Core Field">
+<x-meta id="core-field" label="Polymer Core Field" group="Polymer Core" isContainer>
+
   <template>
-    <core-field icon="search" theme="polymer-ui-light-theme">
+    <core-field icon="search" theme="core-light-theme">
       <core-icon icon="search"></core-icon>
-      <core-input placeholder="text input" flex></core-input>
+      <core-input placeholder="text input" core-flex></core-input>
     </core-field>
   </template>
+  
   <template id="imports">
     <link rel="import" href="core-field.html">
     <link rel="import" href="../core-icon/core-icon.html">
     <link rel="import" href="../core-input/core-input.html">
   </template>
+  
 </x-meta>