In release builds, FLAG_debug_code is statically false. Without LTO,
this information is not available to callers of the various Assert
functions though.
This CL defines the methods as empty if V8_ENABLE_DEBUG_CODE is not set.
This removes some calls from non-LTO builds, and might even slightly
improve LTO builds if we enable more optimizations earlier in the
pipeline.

R=tebbi@chromium.org

Change-Id: I93a8f2f6322053e56f3d0fd8aae73cc3dd62d6ea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3805887
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82255}