Basic tag infrastructure

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index b5de9a3de4ebcd1865090f3e89c4a7716a095255..d1d65e426d6c5cb94dbf117578cfec6c41fc9a43 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -117,6 +117,7 @@ bool IsolateMessageHandler::HandleMessage(Message* message) {
   // TODO(turnidge): Rework collection total dart execution.  This can
   // overcount when other things (gc, compilation) are active.
   TIMERSCOPE(isolate_, time_dart_execution);
+  VMTagScope tagScope(isolate_, VMTag::kScriptTagId);
 
   // If the message is in band we lookup the receive port to dispatch to.  If
   // the receive port is closed, we drop the message without deserializing it.
@@ -332,6 +333,7 @@ Isolate::Isolate()
       object_id_ring_(NULL),
       profiler_data_(NULL),
       thread_state_(NULL),
+      vm_tag_(VMTag::kVMTagId),
       next_(NULL),
       REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_INITIALIZERS)
       REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_SCOPE_INIT)