Cannot use &Trait as argument for generic functions

[14427]

This code fails to compile

trait Foo {
    fn bar(&self);
}

impl int: Foo {
    fn bar(&self) { }
}

fn test<T: Foo>(arr: T) { }

fn main() {
    let x = 5;
    test(&x as &Foo);
}

with: mismatched types: expected@foobut found&/Foo(trait storage differs: expected @ but found &)

This is with the current master.

[catamorphism]

May be related to #3794

[pcwalton]

This is by design.