More tolerance for improperly quoted attribute values

<div style="foo> would previously result in a plain-text tag. We now try
harder to mimic the more lenient PHP parser behavior by still recognizing this
as an attribute value and thus the entire tag as.. a tag.

Now also handled:

{|
| style="foo| bar
|}

No changes in parserTests (TODO: add one!)

Change-Id: I951a102de53dc24ce9a106996af7a71bcbf53023