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

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

 /**
 Use `Polymer.PaperDialogBehavior` and `paper-dialog-shared-styles.html` to implement a Material Design
 dialog.
 
 For example, if `<paper-dialog-impl>` implements this behavior:
 
     <paper-dialog-impl>
         <h2>Header</h2>
         <div>Dialog body</div>
         <div class="buttons">
             <paper-button dialog-dismiss>Cancel</paper-button>
             <paper-button dialog-confirm>Accept</paper-button>
         </div>
     </paper-dialog-impl>
 
 `paper-dialog-shared-styles.html` provide styles for a header, content area, and an action area for buttons.
 Use the `<h2>` tag for the header and the `buttons` class for the action area. You can use the
 `paper-dialog-scrollable` element (in its own repository) if you need a scrolling content area.
 
 Use the `dialog-dismiss` and `dialog-confirm` attributes on interactive controls to close the
 dialog. If the user dismisses the dialog with `dialog-confirm`, the `closingReason` will update
 to include `confirmed: true`.
 
 ### Accessibility
 
 This element has `role="dialog"` by default. Depending on the context, it may be more appropriate
 to override this attribute with `role="alertdialog"`.
 
-If `modal` is set, the element will set `aria-modal` and prevent the focus from exiting the element.
+If `modal` is set, the element will prevent the focus from exiting the element.
 It will also ensure that focus remains in the dialog.
 
 @hero hero.svg
 @demo demo/index.html
 @polymerBehavior Polymer.PaperDialogBehavior
 */
 
   Polymer.PaperDialogBehaviorImpl = {
 
     hostAttributes: {
@@ skipping 22 matching lines @@
     },
 
     ready: function () {
       // Only now these properties can be read.
       this.__prevNoCancelOnOutsideClick = this.noCancelOnOutsideClick;
       this.__prevNoCancelOnEscKey = this.noCancelOnEscKey;
       this.__prevWithBackdrop = this.withBackdrop;
     },
 
     _modalChanged: function(modal, readied) {
-      if (modal) {
-        this.setAttribute('aria-modal', 'true');
-      } else {
-        this.setAttribute('aria-modal', 'false');
-      }
-
       // modal implies noCancelOnOutsideClick, noCancelOnEscKey and withBackdrop.
       // We need to wait for the element to be ready before we can read the
       // properties values.
       if (!readied) {
         return;
       }
 
       if (modal) {
         this.__prevNoCancelOnOutsideClick = this.noCancelOnOutsideClick;
         this.__prevNoCancelOnEscKey = this.noCancelOnEscKey;
@@ skipping 32 matching lines @@
           event.stopPropagation();
           break;
         }
       }
     }
 
   };
 
   /** @polymerBehavior */
   Polymer.PaperDialogBehavior = [Polymer.IronOverlayBehavior, Polymer.PaperDialogBehaviorImpl];