[iOS] Disable fullscreen for SadTab.

Additionally, this CL updates CRWGenericContentView's contentSize
adjustment logic to ensure that scrolling doesn't get disabled.

Bug: 807957
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Idf48f9b79966520f31477b0a58415eb286f037ae
Reviewed-on: https://chromium-review.googlesource.com/917642
Reviewed-by: Eugene But <eugenebut@chromium.org>
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#537450}(cherry picked from commit e8bbb37f4c9a26f147c5623ef88dd7828a53d83b)
Reviewed-on: https://chromium-review.googlesource.com/933304
Cr-Commit-Position: refs/branch-heads/3325@{#563}
Cr-Branched-From: bc084a8b5afa3744a74927344e304c02ae54189f-refs/heads/master@{#530369}
4 files changed