tree e93b3117abbd191745fa8486e0a6e1540428d55a
parent 3582e30d8ec4b0cf8c2768d2c628a4be819ba5c6
author Brian Wilkerson <brianwilkerson@google.com> 1527081116 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org> 1527081116 +0000

Make peek return null when the stack is empty

Change-Id: I73cea25140ad1123ff1a8cb1bca1c69742d3d6f7
Reviewed-on: https://dart-review.googlesource.com/56201
Reviewed-by: Dan Rubel <danrubel@google.com>
Reviewed-by: Peter von der Ahé <ahe@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>