With this CL we share code among the wasm fuzzers which construct a
module and run it in the interpreter and as compiled code.The fuzzers
themselves only contain the code now which creates the module and the
parameters.

BUG=v8:6325
R=eholk@chromium.org

Change-Id: I1c2d8b013531c86cb27837f1b8ec89d2688c536b
Reviewed-on: https://chromium-review.googlesource.com/490048
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Brad Nelson <bradnelson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45156}