Stops dropping several messages to the RenderView when a RenderViewHost is created for prerendering.  In particular, the ViewMsg_WasHidden message was being dropped, which prevents unneeded paint events, as was ViewMsg_AllowScriptToClose.
Stops dropping several messages to the RenderView when
a RenderViewHost is created for prerendering.  In particular,
the ViewMsg_WasHidden message was being dropped, which
prevents unneeded paint events, as was
ViewMsg_AllowScriptToClose.

BUG=none
TEST=none
Review URL: http://codereview.chromium.org/6820070

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@81418 0039d316-1c4b-4281-b951-d872f2087c98

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