Make "length" and "BYTES_PER_ELEMENT" properties of typed arrays accessible.

test/mjsunit/external-array.js

 // Copyright 2011 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
@@ skipping 20 matching lines @@
   a[1] = 0;
 }
 
 var a = new Int32Array(2);
 for (var i = 0; i < 1000000; i++) {
   f(a);
 }
 
 assertEquals(0, a[0]);
 assertEquals(0, a[1]);
+
+// Test the correct behavior of the |length| property (which is read-only).
+a = new Int32Array(42);
+assertEquals(42, a.length);
+a.length = 2;
+assertEquals(42, a.length);
+assertTrue(delete a.length);
+a.length = 2
+assertEquals(2, a.length);
+
+// Test the correct behavior of the |BYTES_PER_ELEMENT| property (which is
+// "constant", but not read-only).
+a = new Int32Array(2);
+assertEquals(4, a.BYTES_PER_ELEMENT);
+a.BYTES_PER_ELEMENT = 42;
+assertEquals(42, a.BYTES_PER_ELEMENT);
+a = new Uint8Array(2);
+assertEquals(1, a.BYTES_PER_ELEMENT);
+a = new Int16Array(2);
+assertEquals(2, a.BYTES_PER_ELEMENT);
+