Document attribute charset and its aliases to return UTF-8

LayoutTests/dom/xhtml/level3/core/documentgetinputencoding02.js

 /*
 Copyright © 2001-2004 World Wide Web Consortium,
 (Massachusetts Institute of Technology, European Research Consortium
 for Informatics and Mathematics, Keio University). All
 Rights Reserved. This work is distributed under the W3C® Software License [1] in the
 hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
 [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 */
@@ skipping 86 matching lines @@
       domImpl = doc.implementation;
 docElem = doc.documentElement;
 
       rootNS = docElem.namespaceURI;
 
       rootName = docElem.tagName;
 
       newDoc = domImpl.createDocument(rootNS,rootName,nullDocType);
       encodingName = newDoc.inputEncoding;
 
-      assertNull("documentgetinputencoding02",encodingName);
+      assertEquals("documentgetinputencoding02", "UTF-8".toLowerCase(), encodingName.toLowerCase());

[dominicc (has gone to gerrit), 2015/06/22 01:23:31]

The spec your change mentions links to this to explain what the name of UTF-8
is:

https://encoding.spec.whatwg.org/#names-and-labels

And what you're asserting here accepts invalid names and doesn't accept all of
the valid ones (you're missing "unicode-1-1-utf-8".) Write an accurate
assertion. Unless there's a spec I'm missing... link?

[Habib Virji, 2015/06/22 14:07:30]

The spec link I mentioned was to emphasise it does not return null but rather
utf-8. Both Gecko and Blink set the value as UTF-8 and not utf-8, utf8 or
unicode-1-1-utf-8. I have updated the test to reflect this.

[philipj_slow, 2015/06/23 08:32:56]

"utf8" and "unicode-1-1-utf-8" don't matter here, those are labels that map to
the internal enum or atomic string representing UTF-8, while this should be
testing how that enum or atomic string is represented when converted back to a
string.

 
 }
 
 function runTest() {
    documentgetinputencoding02();
 }