Compiler fails with docstrings over constructor

[strangeglyph]

Currently, class constructors can not be documented with the /** */-style docstrings, else the compiler complains about unexpected tokens.

This code:

fn main() {}

class foo {

    let bar: bool;

    /**
     * Creates a foo object
     */
    new() {
        self.bar = true;
        io::println("foo");
    }
}

produces the following output:

testpad.rs:10:4: 10:7 error: unexpected token: 'new'
testpad.rs:10     new() {
                  ^~~

[catamorphism]

Thanks for the report -- it turns out doc comments are represented in the compiler as attributes, so this is a dup of #2660. That's certainly not obvious, though.