Don't convert dictionary sloppy arguments to fast double mode.

test/mjsunit/regress/regress-dictionary-to-fast-arguments.js

Index: test/mjsunit/regress/regress-dictionary-to-fast-arguments.js
diff --git a/test/mjsunit/regress/regress-store-global-proxy.js b/test/mjsunit/regress/regress-dictionary-to-fast-arguments.js
similarity index 64%
copy from test/mjsunit/regress/regress-store-global-proxy.js
copy to test/mjsunit/regress/regress-dictionary-to-fast-arguments.js
index c85531c5fd917daa67b54e87141a164b90f3729b..f12679a663d336fa2fd321f0b8f9a48282fef307 100644
--- a/test/mjsunit/regress/regress-store-global-proxy.js
+++ b/test/mjsunit/regress/regress-dictionary-to-fast-arguments.js
@@ -2,11 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-delete Object.prototype.__proto__;
-
-function f() {
-  this.toString = 1;
+function f(a, b) {
+  for (var i = 10000; i > 0; i--) {
+    arguments[i] = 0;
+  }
 }
 
-f.apply({});
-f();
+f(1.5, 2.5);