This removes the above flag definition. The flag is no longer needed as
the default implementation is more than capable of faking presence of
handling of try-catch and try-finally constructs by now.

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

Review URL: https://codereview.chromium.org/1603063003

Cr-Commit-Position: refs/heads/master@{#33402}