ES6: Add support for Set and Map clear method

test/mjsunit/harmony/collections.js

Index: test/mjsunit/harmony/collections.js
diff --git a/test/mjsunit/harmony/collections.js b/test/mjsunit/harmony/collections.js
index 6698a334882f53ae80653b6491cbd2e3f521a313..0219f39364d97a6859037a3f48de87dcefcd8ae3 100644
--- a/test/mjsunit/harmony/collections.js
+++ b/test/mjsunit/harmony/collections.js
@@ -355,3 +355,18 @@ 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);