The regexp interpreter holds several unhandlified references to heap
objects, and is thus within a DisallowHeapAllocation scope. But there
are two situations in which we can and do allocate safely:

1. When creating & throwing a stack overflow exception. The interpreter
   aborts afterwards, and thus possible-moved objects are never used.
2. When handling interrupts. We manually relocate unhandlified references
   after interrupts have run.

This CL explicitly allows allocations on stack overflows.

Isolate::StackOverflow allocates heap objects.

Bug: chromium:940722, v8:8724
Change-Id: I74ef6f0dd7a30bd55f49a7bc0f2f6ac82adbeda8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1518174Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60191}