If two modules use lazy compilation, and one imports a function of
another, we are unwrapping the js-to-wasm wrapper of the export. This
was failing so far, because during unwrapping we did not find the wasm
code.
This CL fixes this by also recognizing WasmCompileLazy stubs as "wasm
code".

R=ahaas@chromium.org

Bug: chromium:779569, v8:5991
Change-Id: If2260c3721e3746a7635b9d0182fd520df2fb773
Reviewed-on: https://chromium-review.googlesource.com/771672
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49405}