Description:
------------
HTML data attribute names can contain periods:

`<p data-1.5>This is valid in HTML5</p>`

DOMDocument::loadHtml does not properly parse the line above due to the period. 
It changes the 1.5 to 1 and/or throws an error:

Warning: DOMDocument::loadHTML() [domdocument.loadhtml]: error parsing attribute 
name in Entity

Please see:
http://www.w3.org/TR/html-markup/syntax.html#syntax-attributes
http://stackoverflow.com/questions/13283699/sanitize-attribute-name

I am using Dreamhost:
PHP version: 5.3.13 (FastCGI)
PHP build date: 2012-06-07

Test script:
---------------
<?php 

# this throws an error:
$dom = new DOMDocument;
$dom->loadHtml('<a data-1.5="value"></a>');
echo $dom->saveHtml();

# this works fine:
$dom = new DOMDocument;
$a = $dom->createElement('a');
$a->setAttribute('data-1.5', 'value');
$dom->appendChild($a);
echo $dom->saveHtml();