Implement a part of ProcessingInstruction by using PrivateScript

Source/core/dom/Document.idl

 /*
  * Copyright (C) 2006, 2007, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006, 2007 Samuel Weinig <sam@webkit.org>
  *
  * 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 197 matching lines @@
     readonly attribute DOMString visibilityState;
     readonly attribute boolean hidden;
 
     // Deprecated prefixed page visibility API.
     // TODO(davidben): This is a property so attaching a deprecation warning results in false positives when outputting
     // document in the console. It's possible http://crbug.com/43394 will resolve this.
     [MeasureAs=PrefixedPageVisibility, ImplementedAs=visibilityState] readonly attribute DOMString webkitVisibilityState;
     [MeasureAs=PrefixedPageVisibility, ImplementedAs=hidden] readonly attribute boolean webkitHidden;
 
     readonly attribute HTMLScriptElement currentScript;
+
+    // Internal API for XSLT
+    [OnlyExposedToPrivateScript] void applyXSLTransform(ProcessingInstruction styleSheet);
+    [OnlyExposedToPrivateScript] readonly attribute Document transformSourceDocument;

[abarth-chromium, 2014/08/05 18:51:41]

I'm concerned about adding a bunch of private APIs to support XSLT-in-JS.  Do
you have a design doc that explains what private APIs we'll need?

It seems like applyXSLTransform and transformSourceDocument could be implemented
in JavaScript.  Is that the eventual plan?  For example, you could imagine
implementing XSLT processing directives entirely in JavaScript based on
window.XSLTProcessor...  In that approach, you wouldn't need these private APIs.

[tasak, 2014/08/06 02:52:03]

Yeah, I would like to remove applyXSLTransform and transformDocument from
Document.{h,cpp}.

However, I think, probably we need C++ special method for PrivateScript, i.e.
- setXSLStyleSheet, and
- createDocumentFromSource

setXSLStyleSheet is a special method to specify XSLStyleSheet, but
XSLTProcessor.idl provides importStyleSheet.

createDocumentFromSource replaces a current frame's document, e.g. XMLDocument
(before applying XSLStyleSheet) => HTMLDocument (after applying XSLStyleSheet).

The above methods are used in Document::applyXSLTransform but not public in web.

My plan is:
- some part of C++ applyXSLTransform will be re-implemented by using 
Javascript,
- the left C++ applyXSLTransform is moved into XSLTProcessor (private method for
PrivateScript).
- transformSourceDocument will be re-implemented by using Javascript

 };
 
 Document implements GlobalEventHandlers;
 Document implements ParentNode;