Restrict immediate operands to smi where only smis are supported.

tests/language/inline_closure_with_constant_arguments.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Test inlining of a closure call with constant propagation.
+primeForSmis(bool b) {
+  smi_op(a, b) => a + b;
+  if (b) {
+    return smi_op(1, 2);
+  } else {
+    return smi_op(true, false);
+  }
+}
+
+
+main() {
+  for (var i=0; i<2000; i++) {
+    Expect.equals(3, primeForSmis(true));
+  }
+}