Add corelib tests

test/codegen/corelib/regress_r21715_test.dart

Index: test/codegen/corelib/regress_r21715_test.dart
diff --git a/test/codegen/language/rewrite_assign_test.dart b/test/codegen/corelib/regress_r21715_test.dart
similarity index 53%
copy from test/codegen/language/rewrite_assign_test.dart
copy to test/codegen/corelib/regress_r21715_test.dart
index 5379a6ca35bf171a8d2f276529597b1355e26a57..5a0ef73d9369efcdc5c89244bfcca25cf1299657 100644
--- a/test/codegen/language/rewrite_assign_test.dart
+++ b/test/codegen/corelib/regress_r21715_test.dart
@@ -2,25 +2,16 @@
 // 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.
 
+// VMOptions=--optimization_counter_threshold=5 --no-background_compilation
+
 import "package:expect/expect.dart";
 
-bar(x,y) {}
-
-foo(b) {
-  var x, y;
-  if (b) {
-    x = 1;
-    y = 2;
-  } else {
-    x = 2;
-    y = 1;
-  }
-  bar(x,y);
-  bar(x,y);
-  return x;
-}
+sll(x, shift) => x << shift;
 
 main() {
-    Expect.equals(1, foo(true));
-    Expect.equals(2, foo(false));
+  for (int i = 0; i < 10; i++) {
+    var x = 0x50000000;
+    var shift = 34;
+    Expect.equals(sll(x, shift), 0x14000000000000000);
+  }
 }