Add test case that checks that class members must be prefixed with "self"

Closes #2289.

src/test/compile-fail/class-missing-self.rs

@@ -0,0 +1,15 @@
+class cat {
+  priv {
+    let mut meows : uint;
+    fn sleep() { loop{} }
+    fn meow() {
+      #error("Meow");
+      meows += 1u; //! ERROR unresolved name
+      sleep();     //! ERROR unresolved name
+    }
+  }
+
+  new(in_x : uint) { self.meows = in_x; }
+}
+
+ fn main() { }