This required splitting wasm-run-utils.h in header and implementation,
since the anonymous namespace in wasm-run-utils.h is now gone.
This is a reasonable refactoring in itself.

R=titzer@chromium.org
CC=mstarzinger@chromium.org, mostynb@opera.com

Bug: chromium:746958
Change-Id: I0f3b30fef1865cd88eca37b69d0c3a9eb19e77ea
Reviewed-on: https://chromium-review.googlesource.com/647587Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47773}