[runtime] Implement %_ToLength via ToLengthStub.

test/mjsunit/harmony/to-length.js

+// Copyright 2015 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.
+
+// Flags: --allow-natives-syntax
+
+assertEquals(0, %ToLength(NaN));
+assertEquals(0, %_ToLength(NaN));
+
+assertEquals(0, %ToLength(-Infinity));
+assertEquals(0, %_ToLength(-Infinity));
+
+assertEquals(0, %ToLength(0));
+assertEquals(0, %_ToLength(0));
+
+assertEquals(0, %ToLength(.5));
+assertEquals(0, %_ToLength(.5));
+
+assertEquals(42, %ToLength(42.99999));
+assertEquals(42, %_ToLength(42.99999));
+
+assertEquals(9007199254740991, %ToLength(9007199254740991));
+assertEquals(9007199254740991, %_ToLength(9007199254740991));
+
+assertEquals(9007199254740991, %ToLength(Infinity));
+assertEquals(9007199254740991, %_ToLength(Infinity));
+
+assertEquals(0, %ToLength(null));
+assertEquals(0, %_ToLength(null));
+
+assertEquals(1, %ToLength(true));
+assertEquals(1, %_ToLength(true));
+
+assertEquals(0, %ToLength(false));
+assertEquals(0, %_ToLength(false));
+
+assertEquals(0, %ToLength(undefined));
+assertEquals(0, %_ToLength(undefined));
+
+assertEquals(0, %ToLength("-1"));
+assertEquals(0, %_ToLength("-1"));
+assertEquals(123, %ToLength("123"));
+assertEquals(123, %_ToLength("123"));
+assertEquals(0, %ToLength("random text"));
+assertEquals(0, %_ToLength("random text"));
+
+assertThrows(function() { %ToLength(Symbol.toPrimitive) }, TypeError);
+assertThrows(function() { %_ToLength(Symbol.toPrimitive) }, TypeError);
+
+var a = { toString: function() { return 54321 }};
+assertEquals(54321, %ToLength(a));
+assertEquals(54321, %_ToLength(a));
+
+var b = { valueOf: function() { return 42 }};
+assertEquals(42, %ToLength(b));
+assertEquals(42, %_ToLength(b));
+
+var c = {
+  toString: function() { return "x"},
+  valueOf: function() { return 123 }
+};
+assertEquals(123, %ToLength(c));
+assertEquals(123, %_ToLength(c));
+
+var d = {
+  [Symbol.toPrimitive]: function(hint) {
+    assertEquals("number", hint);
+    return 987654321;
+  }
+};
+assertEquals(987654321, %ToLength(d));
+assertEquals(987654321, %_ToLength(d));
+
+var e = new Date(0);
+assertEquals(0, %ToLength(e));
+assertEquals(0, %_ToLength(e));