Update CSSOM SmoothScroll Web Platform Test

third_party/WebKit/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 77 matching lines @@
     // https://w3c.github.io/pointerlock/#extensions-to-the-element-interface
     [MeasureAs=ElementRequestPointerLock] void requestPointerLock();
 
     // CSSOM View Module
     // https://dev.w3.org/csswg/cssom-view/#extension-to-the-element-interface
     // FIXME: getClientRect() and getBoundingClientRect() should
     // return DOMRectList and DOMRect respectively.
     ClientRectList getClientRects();
     ClientRect getBoundingClientRect();
 
-    void scrollIntoView(optional (ScrollIntoViewOptions or boolean)? arg);
+    void scrollIntoView();
+    void scrollIntoView((ScrollIntoViewOptions or boolean)? arg);

[foolip, 2017/06/15 08:38:04]

This argument should not be nullable.

[sunyunjia, 2017/06/15 18:00:26]

If I remove the "?", and pass in null or undefined, it would be parsed as an
empty ScrollIntoViewOptions, which has the default value of "center, center".
According to the spec however, if the argument is not specified, the destination
should be "start, nearest". Simon(the author) just submitted another
scrollIntoView
test(https://github.com/w3c/web-platform-tests/commit/1ca1e676dcd995ca693bebfb7c095a977830d89c)
today, and expects the destination to be "start, nearest" for "undefined"
testcase.

[foolip, 2017/06/15 19:41:53]

The "If arg is not specified" case in the spec would be when the method overload
with no arguments is selected. If you make the C++ "void scrollIntoView(bool
align_to_top = true)" have no argument, then you should be able to handle the
"no argument" case internally while keeping the IDL matching the spec. The
easiest way is probably to have the no-argument variant call into the 1-argument
one with a ScrollIntoViewOptionsOrBoolean instance that holds true.

     [RuntimeEnabled=CSSOMSmoothScroll, ImplementedAs=scrollTo] void scroll(optional ScrollToOptions options);
     [RuntimeEnabled=CSSOMSmoothScroll, ImplementedAs=scrollTo] void scroll(unrestricted double x, unrestricted double y);
     [RuntimeEnabled=CSSOMSmoothScroll] void scrollTo(optional ScrollToOptions options);
     [RuntimeEnabled=CSSOMSmoothScroll] void scrollTo(unrestricted double x, unrestricted double y);
     [RuntimeEnabled=CSSOMSmoothScroll] void scrollBy(optional ScrollToOptions options);
     [RuntimeEnabled=CSSOMSmoothScroll] void scrollBy(unrestricted double x, unrestricted double y);
     attribute unrestricted double scrollTop;
     attribute unrestricted double scrollLeft;
     readonly attribute long scrollWidth;
     readonly attribute long scrollHeight;
@@ skipping 30 matching lines @@
     attribute EventHandler oncut;
     attribute EventHandler onpaste;
     attribute EventHandler onsearch;
     attribute EventHandler onselectstart;
     attribute EventHandler onwheel;
 };
 
 Element implements ParentNode;
 Element implements ChildNode;
 Element implements NonDocumentTypeChildNode;