This patch fixes an assert that triggers when removing the last
extension in the list, since the index operator goes out of bounds.
Added a test that fails without the code changes and passes with the
changes.
R=bsalomon@chromium.org
Change-Id: I0d561b150899c178f638dde088af773fddf112d9
Reviewed-on: https://skia-review.googlesource.com/72000
Commit-Queue: Vladimir Levin <vmpstr@chromium.org>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
