Add FLAG_trace_maps

src/runtime/runtime-scopes.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/frames-inl.h"
 #include "src/runtime/runtime-utils.h"
@@ skipping 329 matching lines @@
 
   // Allocate the elements if needed.
   int parameter_count = callee->shared()->formal_parameter_count();
   if (argument_count > 0) {
     if (parameter_count > 0) {
       int mapped_count = Min(argument_count, parameter_count);
       Handle<FixedArray> parameter_map =
           isolate->factory()->NewFixedArray(mapped_count + 2, NOT_TENURED);
       parameter_map->set_map(isolate->heap()->sloppy_arguments_elements_map());
 
-      Handle<Map> map = Map::Copy(handle(result->map()));
+      Handle<Map> map = Map::Copy(handle(result->map()), "NewSloppyArguments");
       map->set_elements_kind(SLOPPY_ARGUMENTS_ELEMENTS);
 
       result->set_map(*map);
       result->set_elements(*parameter_map);
 
       // Store the context and the arguments array at the beginning of the
       // parameter map.
       Handle<Context> context(isolate->context());
       Handle<FixedArray> arguments =
           isolate->factory()->NewFixedArray(argument_count, NOT_TENURED);
@@ skipping 658 matching lines @@
   return Smi::FromInt(frame->GetArgumentsLength());
 }
 
 
 RUNTIME_FUNCTION(RuntimeReference_Arguments) {
   SealHandleScope shs(isolate);
   return __RT_impl_Runtime_GetArgumentsProperty(args, isolate);
 }
 }
 }  // namespace v8::internal