Expose scroll customization for touch to JS (behind REF).

Source/core/dom/Element.idl

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 98 matching lines @@
     // FIXME: style should have [PutForwards=cssText].
     [SameObject, PerWorldBindings] readonly attribute CSSStyleDeclaration style;
 
     // HTML
     // https://html.spec.whatwg.org/#htmlelement
     // FIXME: dataset, focus() and blur() should be on HTMLElement. crbug.com/497274
     [SameObject, PerWorldBindings] readonly attribute DOMStringMap dataset;
     void focus();
     void blur();
 
+    // Scroll Customization API. See crbug.com/410974 for details.
+    [RuntimeEnabled=ScrollCustomization] void applyScroll(ScrollState scrollState);
+    [RuntimeEnabled=ScrollCustomization] void distributeScroll(ScrollState scrollState);
+
     // Non-standard APIs
     // https://www.w3.org/Bugs/Public/show_bug.cgi?id=19962
     [RaisesException, CustomElementCallbacks, MeasureAs=InsertAdjacentElement] Element insertAdjacentElement(DOMString where, Element element);
     [RaisesException, MeasureAs=InsertAdjacentText] void insertAdjacentText(DOMString where, DOMString text);
     [MeasureAs=ElementScrollIntoViewIfNeeded] void scrollIntoViewIfNeeded(optional boolean centerIfNeeded);
     [RaisesException, ImplementedAs=matches, MeasureAs=ElementPrefixedMatchesSelector] boolean webkitMatchesSelector(DOMString selectors);
 
     // Experimental isTapStop API
     [RuntimeEnabled=TabStopAttribute, MeasureAs=TabStopProperty] attribute boolean tabStop;
 
@@ skipping 13 matching lines @@
     [RuntimeEnabled=Touch] attribute EventHandler ontouchcancel;
     [RuntimeEnabled=Touch] attribute EventHandler ontouchend;
     [RuntimeEnabled=Touch] attribute EventHandler ontouchmove;
     [RuntimeEnabled=Touch] attribute EventHandler ontouchstart;
     attribute EventHandler onwheel;
 };
 
 Element implements ParentNode;
 Element implements ChildNode;
 Element implements NonDocumentTypeChildNode;