The behat rule for text selection wasn't working due to the JavaScript not executing properly. I have
also updated the code to traverse all childNodes, which is important if you have text like this:
<p>text1 <b>text2</b> text3</p>
And you are trying to select 'text3'
getAttribute('value') behaves inconsistently with Selenium drivers
(fails on Travis and TeamCity, but works locally). Selenium2Driver
in Mink provides a JS wrapper for getting the value, which is more reliable.
This fixes "insert a link" failures, see https://travis-ci.org/silverstripe/silverstripe-cms/jobs/14281251
Technically a textarea DOM node doesn't have a 'value' attribute,
but rather a HTML content. This used to work, but likely broke either
by updated browser handling or updated selenium logic.
Fixes "Scenario: I can edit title and content and see the changes on draft"
