I incorrectly assumed that ScopeIterator::SetModuleVariableValue gets called
when the frame is the module function.

R=jgruber@chromium.org, kozyatinskiy@chromium.org

Bug: v8:1569, v8:6484
Change-Id: I1fbad8ccde57280149547c78e679527f7a0c89dd
Reviewed-on: https://chromium-review.googlesource.com/535620Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45961}