Implement WeakMap.prototype.clear function.

test/mjsunit/harmony/collections.js

 // Copyright 2012 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 359 matching lines @@
 assertFalse(m.hasOwnProperty('size'));
 for (var i = 0; i < 10; i++) {
   assertEquals(i, m.size);
   m.set(i, i);
 }
 for (var i = 9; i >= 0; i--) {
   m.delete(i);
   assertEquals(i, m.size);
 }
 
-// Test clear
-var a = new Set();
-s.add(42);
-assertTrue(s.has(42));
-s.clear();
-assertFalse(s.has(42));
-assertEquals(0, s.size);
 
-var m = new Map();
-m.set(42, true);
-assertTrue(m.has(42));
-m.clear();
-assertFalse(m.has(42));
-assertEquals(0, m.size);
+// Test Set clear
+(function() {
+  var s = new Set();
+  s.add(42);
+  assertTrue(s.has(42));
+  assertEquals(1, s.size);
+  s.clear();
+  assertFalse(s.has(42));
+  assertEquals(0, s.size);
+})();
+
+
+// Test Map clear
+(function() {
+  var m = new Map();
+  m.set(42, true);
+  assertTrue(m.has(42));
+  assertEquals(1, m.size);
+  m.clear();
+  assertFalse(m.has(42));
+  assertEquals(0, m.size);
+})();
+
+
+// Test WeakMap clear
+(function() {
+  var k = new Object();
+  var w = new WeakMap();
+  w.set(k, 23);
+  assertTrue(w.has(k));
+  assertEquals(23, w.get(k));
+  w.clear();
+  assertFalse(w.has(k));
+  assertEquals(undefined, w.get(k));
+})();