[TLF 2571205] src attribute in <img> tag converts to lower case when using TextConverter.importToFlow with TEXT_FIELD_HTML_FORMAT format

Steps to reproduce:
1. var tempTextFlow:TextFlow = TextConverter.importToFlow('<img src="#FooBar"/>', TextConverter.TEXT_FIELD_HTML_FORMAT);

Actual Results:
<TextFlow xmlns="http://ns.adobe.com/textLayout/2008"><img source="#foobar"/></TextFlow>

Expected Results:
<TextFlow xmlns="http://ns.adobe.com/textLayout/2008"><img source="#FooBar"/></TextFlow>

Workaround (if any):

line#155 (flashx.textLayout.conversion.HtmlImporter - flex_sdk_4.1.0.14532)
_ilgFormatImporter = new CaseInsensitiveTLFFormatImporter(Dictionary,_imageDescription);

should read:
_ilgFormatImporter = new CaseInsensitiveTLFFormatImporter(Dictionary,_imageDescription, false);