Now that FCG is gone, we don't need to have a code-size multiplier to
distinguish Ignition and FCG code sizes.

Bug: v8:6409
Change-Id: I05e5fa2483bfc17e91de22736b66ad27a5aab49b
Reviewed-on: https://chromium-review.googlesource.com/649149
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47819}