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 99 matching lines @@
     [SameObject, PerWorldBindings] readonly attribute CSSStyleDeclaration style;
 
     // HTML
     // https://html.spec.whatwg.org/#htmlelement
     // FIXME: dataset, focus() and blur() should be on HTMLElement.
     [SameObject, PerWorldBindings] readonly attribute DOMStringMap dataset;
     void focus();
     void blur();
 
     // Non-standard APIs
+    // Experimental ScrollCustomization API

[Rick Byers, 2015/04/10 14:51:44]

move this below the below methods (this isn't part of the 'non-standard APIs'
referred to by the above comment - the intent is that it will become standard).

Would be nice to add a bug link for more details on the experiment status.

[tdresser, 2015/05/08 18:23:02]

Moved up, not down, as it leaves the standard APIs contiguous.

Added bug link.

+    [RuntimeEnabled=ScrollCustomization] void applyScroll(ScrollState scrollState);

[Rick Byers, 2015/04/10 14:51:44]

Now that attributes are exposed on the prototype chain, can we do this properly
and make these function-type attributes instead of operations?  You can now
explicitly add the '[ExposeJSAccessors]' attribute to make it clear these
attributes must have getters/setters on the prototype chain (regardless of the
default setting).

This will of course change (hopefully vastly simplify) your bindings logic.  But
my understanding is that there's no longer any reason to depend on the old
broken behavior.

[tdresser, 2015/05/08 18:23:02]

I'm not convinced this is a simplification, but I think it is the right thing to
do.

Done, though there will likely need to be some refactoring done in the bindings
logic before landing.

+    [RuntimeEnabled=ScrollCustomization] void distributeScroll(ScrollState scrollState);
+
     // 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;
 
     // Experimental accessibility API
@@ skipping 12 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;