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

runtime/vm/service.cc

Index: runtime/vm/service.cc
===================================================================
--- runtime/vm/service.cc	(revision 32801)
+++ runtime/vm/service.cc	(working copy)
@@ -297,9 +297,12 @@
       isolate, Script::New(url_str, source_str, RawScript::kLibraryTag));
     library.SetLoadInProgress();
     Dart_EnterScope();  // Need to enter scope for tag handler.
-    const Error& error = Error::Handle(isolate,
-                                       Compiler::Compile(library, script));
-    ASSERT(error.IsNull());
+    {
+      NativeToVmTimerScope timer(isolate);
+      const Error& error = Error::Handle(isolate,
+                                         Compiler::Compile(library, script));
+      ASSERT(error.IsNull());
+    }
     Dart_ExitScope();
     library.SetLoaded();
     // Install embedder default library tag handler again.