Revert 248828 "<webview>: navigating to WebStore should fire a l..."

> <webview>: navigating to WebStore should fire a loadabort instead of crashing.
> 
> All top-level navigations now get plumbed through: BrowserPluginGuest::LoadURLWithParams.
> URL validation now happens there. If a URL is determined to be inappropriate for a <webview>,
> a loadabort event will fire instead of crashing the <webview> guest content.
> 
> BUG=334531
> Test=WebViewTest.Shim_TestNavigateToWebStore
> 
> Review URL: https://codereview.chromium.org/140073002

TBR=fsamuel@chromium.org

Review URL: https://codereview.chromium.org/152783004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249293 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249293