Add more timing information in the VM to track time spent is dart code Vs native code.

runtime/lib/integers.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/bootstrap_natives.h"
 
 #include "include/dart_api.h"
 #include "vm/bigint_operations.h"
 #include "vm/dart_entry.h"
 #include "vm/dart_api_impl.h"
@@ skipping 223 matching lines @@
   return ParseInteger(value);
 }
 
 
 DEFINE_NATIVE_ENTRY(Integer_fromEnvironment, 3) {
   GET_NON_NULL_NATIVE_ARGUMENT(String, name, arguments->NativeArgAt(1));
   GET_NATIVE_ARGUMENT(Integer, default_value, arguments->NativeArgAt(2));
   // Call the embedder to supply us with the environment.
   Dart_EnvironmentCallback callback = isolate->environment_callback();
   if (callback != NULL) {
+    VmToNativeTimerScope timer(isolate);
     Dart_Handle response = callback(Api::NewHandle(isolate, name.raw()));
     if (Dart_IsString(response)) {
       const String& value = String::Cast(
           Object::Handle(isolate, Api::UnwrapHandle(response)));
       const Integer& result = Integer::Handle(ParseInteger(value));
       if (!result.IsNull()) {
         if (result.IsSmi()) return result.raw();
         return result.CheckAndCanonicalize(NULL);
       }
     } else if (Dart_IsError(response)) {
@@ skipping 186 matching lines @@
   // Use the preallocated out of memory exception to avoid calling
   // into dart code or allocating any code.
   const Instance& exception =
       Instance::Handle(isolate->object_store()->out_of_memory());
   Exceptions::Throw(exception);
   UNREACHABLE();
   return 0;
 }
 
 }  // namespace dart