Handle proxies in KeyedStoreIC::Store, instead of just ignoring them.

test/mjsunit/harmony/proxies.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 332 matching lines @@
   var p = create(handler)
   assertEquals(42, p.a = 42)
   assertEquals("a", key)
   assertEquals(42, val)
   assertEquals(43, p["b"] = 43)
   assertEquals("b", key)
   assertEquals(43, val)
   assertEquals(44, p[77] = 44)
   assertEquals("77", key)
   assertEquals(44, val)
+
+  assertEquals(45, (function(n) { return p[n] = 45 })("c"))
+  assertEquals("c", key)
+  assertEquals(45, val)
+  assertEquals(46, (function(n) { return p[n] = 46 })(99))
+  assertEquals("99", key)
+  assertEquals(46, val)
 }
 
 TestSet({
   set: function(r, k, v) { key = k; val = v; return true }
 })
 
 TestSet({
   set: function(r, k, v) { return this.set2(r, k, v) },
   set2: function(r, k, v) { key = k; val = v; return true }
 })
@@ skipping 1794 matching lines @@
 
 TestIsEnumerableThrow(Proxy.create({
   get: function(pr, pk) { throw "myexn" }
 }))
 
 TestIsEnumerableThrow(Proxy.create({
   get: function(pr, pk) {
     return function(k) { throw "myexn" }
   }
 }))