AddCode and AddOwnedCode (from NativeModule), as well as the WasmCode
constructor are using a default value (false) for determining whether
the code is liftoff-compiled or not. This CL removes the default
value and requires each call to these functions/constructors to explicitly
set the value.

Change-Id: Icd4187d1710c774826c9134078ec65845bc98dd7
Reviewed-on: https://chromium-review.googlesource.com/928921
Commit-Queue: Kim-Anh Tran <kimanh@google.com>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51475}