getDecorationRootAndDecoratedRoot should add new user agent shadow roots
https://bugs.webkit.org/show_bug.cgi?id=108301

Reviewed by Hajime Morita.

getDecorationRootAndDecoratedRoot intended to add a second UserAgentShadowRoot
to the input, not just reuse the existing one so it could insert icons into
the inputs. Add back in this behavior for now so we can sort out the right thing
to do.

This behavior is wrong in the current architecture since it means if you had an
input type=submit, add an author shadow root, and then change the type to text
and then the browser decorates it your shadow magically becomes inaccessible since
input.shadowRoot is no longer available. This feature is currently only used for
decorating type=password fields in Chromium with an icon for password generation.

No new tests, there's no way to test this because it's only used in Chromium
by way of the ChromeClient.

* html/shadow/TextFieldDecorationElement.cpp:
(WebCore::getDecorationRootAndDecoratedRoot):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141235 268f45cc-cd09-0410-ab3c-d52691b4dbfc