if a:Ta, do not generate a new type variable when apply spec

[andreinaku]

for example, for the following state(set)

(a:T1 /\ b:T2)

for the expression

a >> b

the expected result is

((a:T1 /\ b:T2 /\ (a >> b):int) ^ (T1 <= int /\ T2 <= int))

(as seen in test_state_apply_spec_11)

[andreinaku]

40953bf982385ee78ecd0e8c6a0d5db99e2bd891