Revert "Fix focus after an interstitial is destroyed. (Merge to M60)"

This reverts commit 8d1af9055ccd9693de85cd2c84f94a84365e875d.

Reason for revert: appears to break lots of tests on beta builder.

Original change's description:
> Fix focus after an interstitial is destroyed. (Merge to M60)
> 
> When an interstitial is created, it steals the page's focus. When it is
> destroyed, it is supposed to return focus to the page, however, since
> the WebContents still thinks an interstitial is being displayed, the
> RenderWidgetHostImpl tries to maintain the focus on the interstitial.
> This CL fixes that by moving the Focus() call into
> WebContentsImpl::DetachInterstitialPage, instead of being called in
> InterstitialPageImpl::Hide.
> 
> TBR=lfg@chromium.org
> 
> (cherry picked from commit 7f1241d2872150eb54fc10268ef03a2d2aca7bce)
> 
> Bug: 739676
> Change-Id: I9eff1af3cb1500cc3f38400ae9e13e553bb0cf54
> Reviewed-on: https://chromium-review.googlesource.com/565172
> Reviewed-by: Charlie Reis <creis@chromium.org>
> Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
> Commit-Queue: Lucas Gadani <lfg@chromium.org>
> Cr-Original-Commit-Position: refs/heads/master@{#485782}
> Reviewed-on: https://chromium-review.googlesource.com/569843
> Cr-Commit-Position: refs/branch-heads/3112@{#605}
> Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}

TBR=creis@chromium.org,alexmos@chromium.org,lfg@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 739676
Change-Id: I52f1f9b44ab4ce1b6ea9b19b7708df1f7bb787aa
Reviewed-on: https://chromium-review.googlesource.com/572460
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Cr-Commit-Position: refs/branch-heads/3112@{#610}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
5 files changed