Remove obsolete comment

Author: catamorphism

src/test/pretty/block-arg-disambig.rs

@@ -1,5 +1,2 @@
-// FIXME: The disambiguation the pretty printer does here
-// is probably not necessary anymore (#2882)
-
 fn blk1(b: fn()) -> fn@() { return fn@() { }; }
 fn test1() { (do blk1 { debug!("hi"); })(); }