[interpreter] Fix GCMole warning.
[interpreter] Fix GCMole warning.

Fix GCMole warning from r29814 (7877c4e0c77b5c2b97678406eab7e9ad6eba4a4d).

BUG=v8:4280
LOG=N
NOTREECHECKS=true
TBR=machenbach,mstarzinger

Review URL: https://codereview.chromium.org/1243893004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#29818}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh