Specialization of ir.Method

[kaihsin]

@kernel
def foo_x(a:int, x: int, y: float):
    p = pure_stmt(prob_ker, x)
    non_pure_stmt(p)

@kernel
def boo(a: int):
        foo(a,3,4.0)

should be able to specialize to:

@kernel
def foo_x(a:int, x: int, y: float):
    p = pure_stmt(prob_ker, x)
    non_pure_stmt(p)

@kernel
def foo_x2(a:int):
    x = 3
    y = 4.0
    p = pure_stmt(prob_ker, x)
    non_pure_stmt(p)


@kernel
def boo(a: int):
        foo_x2(a)