Fix regression in resolution of primitive types

src/test/compile-fail/resolve-primitive-fallback.rs

@@ -0,0 +1,20 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    // Make sure primitive type fallback doesn't work in value namespace
+    std::mem::size_of(u16);
+    //~^ ERROR unresolved name `u16`
+    //~| ERROR this function takes 0 parameters but 1 parameter was supplied
+
+    // Make sure primitive type fallback doesn't work with global paths
+    let _: ::u8;
+    //~^ ERROR type name `u8` is undefined or not in scope
+}