This CL makes several changes to bootstrapper to reduce
code verbosity:

  - Adds an InstallToStringTag helper and uses it everywhere (while
    removing now-redundant comments).
  - Reduces explicit calls to Factory::InternalizeUtf8String
    by adding some overloads of helpers and of JSObject::AddProperty.
  - Uses InstallConstant in all applicable cases.
  - Removes attributes arguments when all callers pass DONT_ENUM.

Change-Id: Ifb5f5102f5fbf89d475045270eeda78a2ee99248
Reviewed-on: https://chromium-review.googlesource.com/c/1385526Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58413}