Add Array.prototype.contains

src/runtime.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this' and
 // it does not push the function onto the stack. This means that you
@@ skipping 558 matching lines @@
   return %NumberToJSUint32(ToNumber(x));
 }
 
 
 // ECMA-262, section 9.5, page 34
 function ToInt32(x) {
   if (%_IsSmi(x)) return x;
   return %NumberToJSInt32(ToNumber(x));
 }
 
+// ES6, section 7.1.15
+function ToLength(x) {
+  if (%_IsSmi(x) && x > 0) return x; // not >= since -0 >= +0

[mathias, 2014/09/18 06:16:32]

Same here.

[Dmitry Lomov (no reviews), 2014/09/18 06:26:46]

if %_IsSmi(x) then x can only be +0  (-0 is not Smi). Feel free to do: 
    if (%_IsSmi(x)) return (x > 0 ? x : 0); 
All Smis are safe

+
+  var len = ToInteger(x);
+  if (len <= 0) return 0;
+  return MathMin(len, $Number.MAX_SAFE_INTEGER);
+}
+
 
 // ES5, section 9.12
 function SameValue(x, y) {
   if (typeof x != typeof y) return false;
   if (IS_NUMBER(x)) {
     if (NUMBER_IS_NAN(x) && NUMBER_IS_NAN(y)) return true;
     // x is +0 and y is -0 or vice versa.
     if (x === 0 && y === 0 && %_IsMinusZero(x) != %_IsMinusZero(y)) {
       return false;
     }
   }
   return x === y;
 }
 
+// ES6, section 7.2.4
+function SameValueZero(x, y) {
+  if (typeof x != typeof y) return false;
+  if (IS_NUMBER(x)) {
+    if (NUMBER_IS_NAN(x) && NUMBER_IS_NAN(y)) return true;
+  }
+  return x === y;
+}
+
 
 /* ---------------------------------
    - - -   U t i l i t i e s   - - -
    ---------------------------------
 */
 
 // Returns if the given x is a primitive value - not an object or a
 // function.
 function IsPrimitive(x) {
   // Even though the type of null is "object", null is still
@@ skipping 45 matching lines @@
   return i;
 }
 
 
 // NOTE: Setting the prototype for Array must take place as early as
 // possible due to code generation for array literals.  When
 // generating code for a array literal a boilerplate array is created
 // that is cloned when running the code.  It is essential that the
 // boilerplate gets the right prototype.
 %FunctionSetPrototype($Array, new $Array(0));