Add test with implemented bits of issue #570.

Author: jwise

src/test/run-pass/const-contents.rs

@@ -0,0 +1,17 @@
+// Issue #570
+
+const lsl : int = 1 << 2;
+const add : int = 1 + 2;
+const addf : float = 1.0f + 2.0f;
+const not : int = !0;
+const notb : bool = !true;
+const neg : int = -(1);
+
+fn main() {
+    assert(lsl == 4);
+    assert(add == 3);
+    assert(addf == 3.0f);
+    assert(not == -1);
+    assert(notb == false);
+    assert(neg == -1);
+}