This way we can teach the debugger to disable liveness analysis when
running with (potential) breakpoints, so that the developers always
have (read) access to all scoped variable values.

Bug: v8:7608, chromium:826613
Change-Id: I7e6cea105f111c99d2620546144201624dfe1d8b
Reviewed-on: https://chromium-review.googlesource.com/985838Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52293}