Chromium now enforces no renderer crashes assertion on browser tests. To
allow an intentional crash test ScopedAllowRendererCrashes needs to be
added.

Chromium changes:

https://chromium.googlesource.com/chromium/src/+/922389129506cc063b83ffddc7e27e0314ead777

commit 922389129506cc063b83ffddc7e27e0314ead777
Author: Lukasz Anforowicz <lukasza@chromium.org>
Date:   Mon Jun 17 20:26:46 2019 +0000

    Start enforcing NoRendererCrashesAssertion in browser tests.

    Change-Id: Iec1b1090a675ff6af74661f5a000c41a9a8df940
    Bug: 972220

https://chromium.googlesource.com/chromium/src/+/96eca2d491cd1153b0674c8e6983312a83d55dcf

commit 96eca2d491cd1153b0674c8e6983312a83d55dcf
Author: Lukasz Anforowicz <lukasza@chromium.org>
Date:   Thu Jun 13 20:46:42 2019 +0000

    Prepare browser tests for NoRendererCrashesAssertion.

    This CL adds ScopedAllowRendererCrashes to browser tests that
    (expectedly or unexpectedly) might trigger a renderer crash.

    Right now a browser test might pass, even if a renderer process crashed
    during the test execution.  After https://crrev.com/c/1650463 a renderer
    crash will trigger an explicit test failure, but before this enforcement
    can start, existing tests that experience renderer crashes (expectedly
    or unexpectedly) need to declare this via ScopedAllowRendererCrashes.

    This CL was uploaded by git cl split.

    R=bengr@chromium.org

    Bug: 972220