v8: fix debug builds on Windows
Adds missing return which fixes Node 8.x debug builds on Windows, while we wait for upstream patch to land.
Fixes: https://github.com/nodejs/node/issues/13392
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
commit message follows commit guidelines
Affected core subsystem(s)
v8