Typically the interpreter returns 0xdeadbeef to indicate an exception.
However, for stack overflows a normal exception is used. The interpreter
requires an activation, however, to deal with normal exceptions. With
this CL we start an activation before we execute the fuzzer input in the
interpreter.

R=clemensh@chromium.org

Bug: chromium:781103
Change-Id: I4fc3a18bfc2076aab9ff7d2324a3311fe222954a
Reviewed-on: https://chromium-review.googlesource.com/776835
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49545}