ast: Don't do oo merge when finding a value if current is a unary.
ast: Don't do oo merge when finding a value if current is a unary.

This was causing the !!0 + !!0 test to write out the wrong opcode. There's no
way to write a sanity test for this, since there's no code introspection. So
prevention of this will rely on checking the sanity's emit results
occasionally.

crasm/lily,crasm/lily,boardwalk/lily,boardwalk/lily,crasm/lily