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

runtime/vm/code_descriptors_test.cc

Index: runtime/vm/code_descriptors_test.cc
===================================================================
--- runtime/vm/code_descriptors_test.cc	(revision 32362)
+++ runtime/vm/code_descriptors_test.cc	(working copy)
@@ -9,6 +9,7 @@
 #include "vm/assembler.h"
 #include "vm/code_descriptors.h"
 #include "vm/compiler.h"
+#include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/native_entry.h"
 #include "vm/parser.h"
@@ -219,6 +220,7 @@
       "}\n";
   // First setup the script and compile the script.
   TestCase::LoadTestScript(kScriptChars, native_resolver);
+  NativeToVmTimerScope timer(Isolate::Current());
   EXPECT(ClassFinalizer::ProcessPendingClasses());
   const String& name = String::Handle(String::New(TestCase::url()));
   const Library& lib = Library::Handle(Library::LookupLibrary(name));