This patch adds FunctionEnvironmentRecord as a subclass of the existing
DeclarativeEnvironmentRecord. Things that are specific to function
environment records move into there, simplifying the base.
Most of the abstract operations related to function environment records
are rewritten to match the spec exactly. I also had to implement
GetThisEnvironment() and GetSuperConstructor() to keep tests working
after the changes, so that's nice as well. :^)
Value.{cpp,h} has become a dumping ground, let's change that.
Things that are directly related to Values (e.g. bitwise/binary ops,
equality related functions) can remain, but everything else that's not a
Value or Object method and globally required (not just a static function
somewhere) is being moved.
Also convert to east-const while we're here.
I haven't touched IteratorOperations.{cpp,h}, it seems fine to still
have those separately.
