Remove all ThisExpression handling
Remove all ThisExpression handling

Before 1.0.7, root-level ThisExpressions are pushed into the globals
object, but are then filtered out since node.name is undefined. In
1.0.7, this behavior is "fixed," since `this` as a global is added to
the output. Unfortunately, this represents an API break and is reverted.
So, for now let's simply remove all ThisExpression handling.

ForbesLindesay/acorn-globals