This is true for environments created by `with` statements, and false
for other (global) object environments.
Also add the WithBaseObject abstract operation while we're here.
To better follow the spec, we need to distinguish between the current
execution context's lexical environment and variable environment.
This patch moves us to having two record pointers, although both of
them point at the same environment records for now.
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.
