Summary:
This diff lifts the Prop.Attribute module out of Prop. This required
moving several Prop functions that depend on Attribute
(find_arithmetic_problem, deallocate_stack_vars, find_equal_formal_path)
and adding numerous calls to Prop.normalize to fix normal/exposed
mismatches. Also note that the type of Prop.normalize is generalized to
allow calling it on normalized props.
Reviewed By: cristianoc
Differential Revision: D3684523
fbshipit-source-id: f37af8b
Josh Berdine