1. Get rid of SwitchIsolateScope as it is not clear when this should be used and there is also a bu…

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 328624b87f05c6b2649b7974d757506d5ddc776d..db95294358158c7b9427a02d4ed10c06e0616782 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -1454,11 +1454,8 @@ static void ShutdownIsolate(uword parameter) {
     }
     Dart::RunShutdownCallback();
   }
-  {
-    // Shut the isolate down.
-    SwitchIsolateScope switch_scope(isolate);
-    Dart::ShutdownIsolate();
-  }
+  // Shut the isolate down.
+  Dart::ShutdownIsolate(isolate);
 }
 
 
@@ -1664,6 +1661,9 @@ void Isolate::Shutdown() {
 
   Thread* thread = Thread::Current();
 
+  // Don't allow anymore dart code to execution on this isolate.
+  ClearStackLimit();
+
   // First, perform higher-level cleanup that may need to allocate.
   {
     // Ensure we have a zone and handle scope so that we can call VM functions.