Introduce experimental natives that are enabled by a runtime flag.

src/flag-definitions.h

 // 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 78 matching lines @@
 #define DEFINE_int(nam, def, cmt) FLAG(INT, int, nam, def, cmt)
 #define DEFINE_float(nam, def, cmt) FLAG(FLOAT, double, nam, def, cmt)
 #define DEFINE_string(nam, def, cmt) FLAG(STRING, const char*, nam, def, cmt)
 #define DEFINE_args(nam, def, cmt) FLAG(ARGS, JSArguments, nam, def, cmt)
 
 //
 // Flags in all modes.
 //
 #define FLAG FLAG_FULL
 
+// Flags for experimental language features.
+DEFINE_bool(harmony_proxies, false, "enable harmony proxies")
+
 // Flags for Crankshaft.
 #ifdef V8_TARGET_ARCH_MIPS
   DEFINE_bool(crankshaft, false, "use crankshaft")
 #else
   DEFINE_bool(crankshaft, true, "use crankshaft")
 #endif
 DEFINE_string(hydrogen_filter, "", "hydrogen use/trace filter")
 DEFINE_bool(use_hydrogen, true, "use generated hydrogen for compilation")
 DEFINE_bool(build_lithium, true, "use lithium chunk builder")
 DEFINE_bool(alloc_lithium, true, "use lithium register allocator")
@@ skipping 439 matching lines @@
 #undef FLAG
 
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META