Reload: Don't free the saved class table while another thread may be reading it.

runtime/vm/unit_test.cc

Index: runtime/vm/unit_test.cc
diff --git a/runtime/vm/unit_test.cc b/runtime/vm/unit_test.cc
index a877a1af1923f5bd0d0fa292335f228c17c8a5a3..b64722473e812c3caaf9aad7415b6a9654a3f5fb 100644
--- a/runtime/vm/unit_test.cc
+++ b/runtime/vm/unit_test.cc
@@ -331,9 +331,13 @@ Dart_Handle TestCase::ReloadTestScript(const char* script) {
 
   result = GetReloadErrorOrRootLibrary();
 
-  Isolate* isolate = Isolate::Current();
-  if (isolate->reload_context() != NULL) {
-    isolate->DeleteReloadContext();
+  {
+    Thread* thread = Thread::Current();
+    TransitionNativeToVM transition(thread);
+    Isolate* isolate = thread->isolate();
+    if (isolate->reload_context() != NULL) {
+      isolate->DeleteReloadContext();
+    }
   }
 
   return result;