opt_invokebuiltin_delegate and opt_invokebuiltin_delegate_leave invokes builtin functions with same parameters of the method. This technique eliminate stack push operations. However, delegation parameters should be completely same as given parameters. (e.g. `def foo(a, b, c) __builtin_foo(a, b, c)` is okay, but __builtin_foo(b, c) is not allowed) This relaxes this restriction. ISeq has a local variables table which includes parameters. For example, the method defined as `def foo(a, b, c) x=y=nil`, then local variables table contains [a, b, c, x, y]. If calling builtin-function with arguments which are sub-array of the lvar table, use opt_invokebuiltin_delegate instruction with start index. For example, `__builtin_foo(b, c)`, `__builtin_bar(c, x, y)` is okay, and so on.