This makes sure that the {WasmModuleObject} has been allocated before
any debug events are fired. Since {WasmScript} objects reference the
module object, it needs to be allocated earlier by now.

R=ahaas@chromium.org
TEST=debugger/regress/regress-crbug-840288
BUG=chromium:840288

Change-Id: I02783ce126c463ac953eb2192acb65f3a5d420a1
Reviewed-on: https://chromium-review.googlesource.com/1050246Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53084}