Still allow WebKit to spiritualize sync

- using gui.DOMPlugin, although we're now crawling the DOM twice when
native DOM setters come into play ...
Deprecate gui.Broadcast.dispatch target argument
Don't read that target
Don't crawl PRE and CODE (fasthack)

TODO: Come up with an interface for this sort of thing...
Preparing the upstream...
Merge pull request #130 from Tradeshift/master

Accept this pull request, or else...