Revert 155801 "Fix touch handler ASSERT when an iframe containin..."

Caused 50% perf regression in parser/html-parser perf test

> Fix touch handler ASSERT when an iframe containing a plugin changes source
> 
> When an iframe's src is changed, Document::removeAllEventListeners is used to 
> clear all event listeners in the document, as a result the parent document
> will clear out any known touch handler for the iframe.  But if the iframe
> contained a plugin, then when that plugin is destroyed it'll try to
> notify the document that it is no longer handling touch events, and (if it's the
> only touch event handler on the document) the parent document will get a duplicate
> removal notification.
> 
> Also, despite Document::removeAllEventListeners telling it's parent document
> it has no more handlers, it now actually clears it's own list too.  
> 
> BUG=254203
> 
> Review URL: https://chromiumcodereview.appspot.com/22301016

TBR=rbyers@chromium.org
BUG=273219

Review URL: https://codereview.chromium.org/22831009

git-svn-id: svn://svn.chromium.org/blink/trunk@156158 bbb929c8-8fbe-4397-9dbb-9b2b20218538