This models function local control flow through try-finally constructs
using a token dispatch mechanism. All paths through the finally block
are assigned a token, at the end of the finally block a switch construct
dispatches according to this token.

R=oth@chromium.org,rmcilroy@chromium.org
BUG=v8:4674
LOG=n

Review URL: https://codereview.chromium.org/1613443002

Cr-Commit-Position: refs/heads/master@{#33465}