Sets the hash default when dictionary is created.
Migrates the hash correctly when the dictionary grows.

Bug: v8:6443, v8:7569
Change-Id: I9195b557796b9bd3d040bd6f4f77d1f9ead4fc7d
Reviewed-on: https://chromium-review.googlesource.com/c/1337744Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58181}