This promotes CompileTimeValue as a seperate struct instead of FixedArray.
This reduces the heap object size by one word (size field of FixedArray)

Change-Id: Id09d9e04c4c1a98aa9fa53b1a44ec17e8cd06f34
Bug: v8:7787, chromium:818642
Reviewed-on: https://chromium-review.googlesource.com/1119918
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54135}