Roll Polymer from 1.5.0 -> 1.6.0 to pick up native CSS custom props

third_party/polymer/v1_0/components-chromium/paper-input/paper-input-behavior-extracted.js

 // Generate unique, monotonically increasing IDs for labels (needed by
   // aria-labelledby) and add-ons.
   Polymer.PaperInputHelper = {};
   Polymer.PaperInputHelper.NextLabelID = 1;
   Polymer.PaperInputHelper.NextAddonID = 1;
 
   /**
    * Use `Polymer.PaperInputBehavior` to implement inputs with `<paper-input-container>`. This
    * behavior is implemented by `<paper-input>`. It exposes a number of properties from
    * `<paper-input-container>` and `<input is="iron-input">` and they should be bound in your
@@ skipping 178 matching lines @@
       autocomplete: {
         type: String,
         value: 'off'
       },
 
       /**
        * If you're using PaperInputBehavior to implement your own paper-input-like
        * element, bind this to the `<input is="iron-input">`'s `autofocus` property.
        */
       autofocus: {
-        type: Boolean
+        type: Boolean,
+        observer: '_autofocusChanged'
       },
 
       /**
        * If you're using PaperInputBehavior to implement your own paper-input-like
        * element, bind this to the `<input is="iron-input">`'s `inputmode` property.
        */
       inputmode: {
         type: String
       },
 
@@ skipping 296 matching lines @@
       // In the Shadow DOM, the `change` event is not leaked into the
       // ancestor tree, so we must do this manually.
       // See https://w3c.github.io/webcomponents/spec/shadow/#events-that-are-not-leaked-into-ancestor-trees.
       if (this.shadowRoot) {
         this.fire(event.type, {sourceEvent: event}, {
           node: this,
           bubbles: event.bubbles,
           cancelable: event.cancelable
         });
       }
+    },
+
+    _autofocusChanged: function() {
+      // Firefox doesn't respect the autofocus attribute if it's applied after
+      // the page is loaded (Chrome/WebKit do respect it), preventing an
+      // autofocus attribute specified in markup from taking effect when the
+      // element is upgraded. As a workaround, if the autofocus property is set,
+      // and the focus hasn't already been moved elsewhere, we take focus.
+      if (this.autofocus && this._focusableElement) {
+
+        // In IE 11, the default document.activeElement can be the page's
+        // outermost html element, but there are also cases (under the
+        // polyfill?) in which the activeElement is not a real HTMLElement, but
+        // just a plain object. We identify the latter case as having no valid
+        // activeElement.
+        var activeElement = document.activeElement;
+        var isActiveElementValid = activeElement instanceof HTMLElement;
+
+        // Has some other element has already taken the focus?
+        var isSomeElementActive = isActiveElementValid &&
+            activeElement !== document.body &&
+            activeElement !== document.documentElement; /* IE 11 */
+        if (!isSomeElementActive) {
+          // No specific element has taken the focus yet, so we can take it.
+          this._focusableElement.focus();
+        }
+      }
     }
   }
 
   /** @polymerBehavior */
   Polymer.PaperInputBehavior = [
     Polymer.IronControlState,
     Polymer.IronA11yKeysBehavior,
     Polymer.PaperInputBehaviorImpl
   ];