Cancel JavaScript dialogs when an interstitial appears.

BUG=295695
TEST=See bug for repro steps.

Review URL: https://chromiumcodereview.appspot.com/24360011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225026 0039d316-1c4b-4281-b951-d872f2087c98
SiteInstance* WebContentsImpl::GetPendingSiteInstance() const {
  RenderViewHost* dest_rvh = render_manager_.pending_render_view_host() ?
      render_manager_.pending_render_view_host() :
      render_manager_.current_host();
  return dest_rvh->GetSiteInstance();
}

SiteInstance* WebContentsImpl::GetPendingSiteInstance() const {
  RenderViewHost* dest_rvh = render_manager_.pending_render_view_host() ?
      render_manager_.pending_render_view_host() :
      render_manager_.current_host();
  return dest_rvh->GetSiteInstance();
}
