Make arguments and caller always be null on native functions (fixes issue 1548 and issue 1643).

src/v8natives.js

Index: src/v8natives.js
===================================================================
--- src/v8natives.js	(revision 9034)
+++ src/v8natives.js	(working copy)
@@ -55,6 +55,15 @@
     var f = functions[i + 1];
     %FunctionSetName(f, key);
     %FunctionRemovePrototype(f);
+    // We match firefox on this, but not Safari (which does not have the
+    // property at all).
+    %IgnoreAttributesAndSetProperty(f, "caller",
+                                    null,
+                                    DONT_ENUM | DONT_DELETE);
+    %IgnoreAttributesAndSetProperty(f, "arguments",
+                                    null,
+                                    DONT_ENUM | DONT_DELETE);
+
     %SetProperty(object, key, f, attributes);
     %SetNativeFlag(f);
   }