Revert "allow fn exprs to omit arg types"

This reverts commit 1ba4ca4c4a.

src/test/compile-fail/omitted-arg-in-item-fn.rs

@@ -1,2 +0,0 @@
-fn foo(x) { //! ERROR expecting ':' but found ')'
-}

src/test/compile-fail/omitted-arg-wrong-types.rs

@@ -1,9 +0,0 @@
-fn let_in<T>(x: T, f: fn(T)) {}
-
-fn main() {
-    let_in(3u, fn&(i) { assert i == 3; });
-    //!^ ERROR expected `uint` but found `int`
-
-    let_in(3, fn&(i) { assert i == 3u; });
-    //!^ ERROR expected `int` but found `uint`
-}

src/test/compile-fail/pptypedef.rs

@@ -1,8 +0,0 @@
-type foo = option<int>;
-
-fn bar(_t: foo) {}
-
-fn main() {
-    // we used to print foo<int>:
-    bar(some(3u)); //! ERROR mismatched types: expected `foo`
-}

src/test/compile-fail/vec-concat-bug.rs

@@ -4,6 +4,7 @@ fn concat<T: copy>(v: [const [const T]]) -> [T] {
     // Earlier versions of our type checker accepted this:
     vec::iter(v) {|&&inner: [T]|
         //!^ ERROR values differ in mutability
+        //!^^ ERROR values differ in mutability
         r += inner;
     }