Reapply "Port regexp tests from V8 to Dart."

tests/corelib/regexp/v8_regexp_utils.dart

Index: tests/corelib/regexp/v8_regexp_utils.dart
diff --git a/tests/corelib/regexp/v8_regexp_utils.dart b/tests/corelib/regexp/v8_regexp_utils.dart
new file mode 100644
index 0000000000000000000000000000000000000000..83e56d09eb3b2afaae37381241feb38f762ecbc9
--- /dev/null
+++ b/tests/corelib/regexp/v8_regexp_utils.dart
@@ -0,0 +1,49 @@
+// Copyright (c) 2014, 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.
+
+// Utility functions to easily port V8 tests.
+
+import "package:expect/expect.dart";
+
+void assertEquals(actual, expected, [String message = null]) {
+  Expect.equals(actual, expected, message);
+}
+void assertTrue(actual, [String message = null]) { Expect.isTrue(actual, message); }
+void assertFalse(actual, [String message = null]) { Expect.isFalse(actual, message); }
+void assertThrows(fn, [num testid = null]) {
+  Expect.throws(fn, null, "Test $testid");
+}
+void assertNull(actual, [num testid = null]) {
+  Expect.isNull(actual, "Test $testid");
+}
+
+void assertToStringEquals(str, match, num testid) {
+  var actual = [];
+  for (int i = 0; i <= match.groupCount; i++) {
+    var g = match.group(i);
+    actual.add((g == null) ? "" : g);
+  }
+  Expect.equals(str, actual.join(","), "Test $testid");
+}
+
+void shouldBeTrue(actual) { Expect.isTrue(actual); }
+void shouldBeFalse(actual) { Expect.isFalse(actual); }
+void shouldBeNull(actual) { Expect.isNull(actual); }
+
+void shouldBe(actual, expected, [String message = null]) {
+  if (expected == null) {
+    Expect.isNull(actual, message);
+  } else {
+    Expect.equals(expected.length, actual.groupCount + 1);
+    for (int i = 0; i <= actual.groupCount; i++) {
+      Expect.equals(expected[i], actual.group(i), message);
+    }
+  }
+}
+
+Match firstMatch(String str, RegExp pattern) => pattern.firstMatch(str);
+List<String> allStringMatches(String str, RegExp pattern) =>
+    pattern.allMatches(str).map((Match m) => m.group(0)).toList();
+
+void description(str) { }