This removes the {IsWasm} and {IsAsmJs} methods, which tested a
ModuleOrigin for a specific constant.
These methods do not comply with our naming conventions, and we don't
have such methods for other enums.

Drive-by: Refactor the code which used these methods for better
readability and maintainability.

R=ahaas@chromium.org, kschimpf@chromium.org
BUG=v8:6474

Change-Id: I98eb4dba5420eaa9452ae6f27598ec8b581a0984
Reviewed-on: https://chromium-review.googlesource.com/530229Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45888}