Rearrange things such that when creating the environment we have
access to the subject of compilation (either a full JSFunction or
just a FunctionBlueprint).

Bug: v8:7790
Change-Id: I03cc4701eb8bc1ed44c8381f4ab82da5f9b840b8
Reviewed-on: https://chromium-review.googlesource.com/c/1434374
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59091}