Fixed ranges are used to express register constraints in the
allocator. This change splits these fixed ranges into one for
normal code and deferred code. The former are handeled as before
whereas the latter are only made visible while allocating
registers for deferred code.

This prevents forward looking decisions in normal code to be
impacted by register constraints from deferred code.

Change-Id: I67d562bb41166194e62765d5ab051bc961054fc7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1477742
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60322}