Add corelib tests

test/codegen/corelib/string_trim_test.dart

Index: test/codegen/corelib/string_trim_test.dart
diff --git a/test/codegen/corelib/string_trim_test.dart b/test/codegen/corelib/string_trim_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..6049af9e1c705d178de7aa0851ad8236602c749a
--- /dev/null
+++ b/test/codegen/corelib/string_trim_test.dart
@@ -0,0 +1,25 @@
+// Copyright (c) 2011, 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.
+
+import "package:expect/expect.dart";
+
+class StringTrimTest {
+  static testMain() {
+    Expect.equals("", " ".trim());
+    Expect.equals("", "     ".trim());
+    var a = "      lots of space on the left";
+    Expect.equals("lots of space on the left", a.trim());
+    a = "lots of space on the right           ";
+    Expect.equals("lots of space on the right", a.trim());
+    a = "         lots of space           ";
+    Expect.equals("lots of space", a.trim());
+    a = "  x  ";
+    Expect.equals("x", a.trim());
+    Expect.equals("", " \t \n \r ".trim());
+  }
+}
+
+main() {
+  StringTrimTest.testMain();
+}