This fixes a bug found by the fuzzer where we would attempt to
dereference a null handle if memory allocation failed. In this case,
the failure was because the amount of memory requested was above V8's
hardcoded limit.

BUG= https://bugs.chromium.org/p/chromium/issues/detail?id=666741

Review-Url: https://codereview.chromium.org/2514983002
Cr-Commit-Position: refs/heads/master@{#41158}