The RareData objects contain fields that often absent in CodeEntry'es.
They are created as needed when a corresponding field is added.
This reduces CodeEntry size on x64 by 40% from 136 to 80 bytes.

BUG=v8:7719

Change-Id: I1f3c6255aa2f228895e835b536c743396131db31
Reviewed-on: https://chromium-review.googlesource.com/1045885Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53039}