Parser::MaybeResetCharacterStream calls Scope::ContainsAsmModule which
recursively checks whether a Scope is an asm module or any of its
sub-scopes. This is sub-optimal for deeply nested scopes and many
functions which do not contain any asm modules.

Drive-by-fix:
- rename Scope::asm_module to Scope::is_asm_module


Change-Id: I922270c608b54c6525f0672ead4aca90f57a6551
Reviewed-on: https://chromium-review.googlesource.com/c/1360636Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58288}