This adds new methods to String object:

test/mjsunit/harmony/string-contains.js

Index: test/mjsunit/harmony/string-contains.js
diff --git a/test/mjsunit/harmony/string-contains.js b/test/mjsunit/harmony/string-contains.js
new file mode 100644
index 0000000000000000000000000000000000000000..983c4cf50d12a90e118dc69afc6596fd6db02ed6
--- /dev/null
+++ b/test/mjsunit/harmony/string-contains.js
@@ -0,0 +1,152 @@
+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --harmony-strings
+
+assertEquals(1, String.prototype.contains.length);
+
+var reString = "asdf[a-z]+(asdf)?";
+assertTrue(reString.contains("[a-z]+"));
+assertTrue(reString.contains("(asdf)?"));
+
+// Random greek letters
+var twoByteString = "\u039a\u0391\u03a3\u03a3\u0395";
+
+// Test single char pattern
+assertTrue(twoByteString.contains("\u039a"), "Lamda");
+assertTrue(twoByteString.contains("\u0391"), "Alpha");
+assertTrue(twoByteString.contains("\u03a3"), "First Sigma");
+assertTrue(twoByteString.contains("\u03a3",3), "Second Sigma");
+assertTrue(twoByteString.contains("\u0395"), "Epsilon");
+assertFalse(twoByteString.contains("\u0392"), "Not beta");
+
+// Test multi-char pattern
+assertTrue(twoByteString.contains("\u039a\u0391"), "lambda Alpha");
+assertTrue(twoByteString.contains("\u0391\u03a3"), "Alpha Sigma");
+assertTrue(twoByteString.contains("\u03a3\u03a3"), "Sigma Sigma");
+assertTrue(twoByteString.contains("\u03a3\u0395"), "Sigma Epsilon");
+
+assertFalse(twoByteString.contains("\u0391\u03a3\u0395"),
+    "Not Alpha Sigma Epsilon");
+
+//single char pattern
+assertTrue(twoByteString.contains("\u0395"));
+
+assertThrows("String.prototype.contains.call(null, 'test')", TypeError);
+assertThrows("String.prototype.contains.call(null, null)", TypeError);
+assertThrows("String.prototype.contains.call(undefined, undefined)", TypeError);
+
+assertThrows("String.prototype.contains.apply(null, ['test'])", TypeError);
+assertThrows("String.prototype.contains.apply(null, [null])", TypeError);
+assertThrows("String.prototype.contains.apply(undefined, [undefined])", TypeError);
+
+var TEST_INPUT = [{
+  msg: "Empty string", val: ""
+}, {
+  msg: "Number 1234.34", val: 1234.34
+}, {
+  msg: "Integer number 0", val: 0
+}, {
+  msg: "Negative number -1", val: -1
+}, {
+  msg: "Boolean true", val: true
+}, {
+  msg: "Boolean false", val: false
+}, {
+  msg: "Regular expression /\d+/", val: /\d+/
+}, {
+  msg: "Empty array []", val: []
+}, {
+  msg: "Empty object {}", val: {}
+}, {
+  msg: "Array of size 3", val: new Array(3)
+}];
+
+var i = 0;
+var l = TEST_INPUT.length;
+
+for (; i < l; i++) {
+  var e = TEST_INPUT[i];
+  var v = e.val;
+  var s = String(v);
+  assertTrue(s.contains(v), e.msg);
+  assertTrue(String.prototype.contains.call(v, v), e.msg);
+  assertTrue(String.prototype.contains.apply(v, [v]), e.msg);
+}
+
+// Test cases found in FF
+assertTrue("abc".contains("a"));
+assertTrue("abc".contains("b"));
+assertTrue("abc".contains("abc"));
+assertTrue("abc".contains("bc"));
+assertFalse("abc".contains("d"));
+assertFalse("abc".contains("abcd"));
+assertFalse("abc".contains("ac"));
+assertTrue("abc".contains("abc", 0));
+assertTrue("abc".contains("bc", 0));
+assertFalse("abc".contains("de", 0));
+assertTrue("abc".contains("bc", 1));
+assertTrue("abc".contains("c", 1));
+assertFalse("abc".contains("a", 1));
+assertFalse("abc".contains("abc", 1));
+assertTrue("abc".contains("c", 2));
+assertFalse("abc".contains("d", 2));
+assertFalse("abc".contains("dcd", 2));
+assertFalse("abc".contains("a", 42));
+assertFalse("abc".contains("a", Infinity));
+assertTrue("abc".contains("ab", -43));
+assertFalse("abc".contains("cd", -42));
+assertTrue("abc".contains("ab", -Infinity));
+assertFalse("abc".contains("cd", -Infinity));
+assertTrue("abc".contains("ab", NaN));
+assertFalse("abc".contains("cd", NaN));
+assertFalse("xyzzy".contains("zy\0", 2));
+
+var dots = Array(10000).join('.');
+assertFalse(dots.contains("\x01", 10000));
+assertFalse(dots.contains("\0", 10000));
+
+var myobj = {
+  toString: function () {
+    return "abc";
+  },
+  contains: String.prototype.contains
+};
+assertTrue(myobj.contains("abc"));
+assertFalse(myobj.contains("cd"));
+
+var gotStr = false;
+var gotPos = false;
+myobj = {
+  toString: function () {
+    assertFalse(gotPos);
+    gotStr = true;
+    return "xyz";
+  },
+  contains: String.prototype.contains
+};
+