Unreviewed build fix. Remove assertion that doesn't make sense anymore since the
page does not give us access to the Chrome pointer directly anymore.

Patch by Gustavo Noronha Silva <gustavo.noronha@collabora.com> on 2013-05-17

* webkit/webkitwebview.cpp:
(WebKit::kit):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150256 268f45cc-cd09-0410-ab3c-d52691b4dbfc