VM: Prohibit reload when throwing or processing language errors.

runtime/vm/exceptions.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/exceptions.h"
 
 #include "platform/address_sanitizer.h"
 
 #include "lib/stacktrace.h"
 
@@ skipping 955 matching lines @@
     case kCyclicInitializationError:
       library = Library::CoreLibrary();
       class_name = &Symbols::CyclicInitializationError();
       break;
     case kCompileTimeError:
       library = Library::CoreLibrary();
       class_name = &Symbols::_CompileTimeError();
       break;
   }
 
+  Thread* thread = Thread::Current();
+  NoReloadScope no_reload_scope(thread->isolate(), thread);
   return DartLibraryCalls::InstanceCreate(library, *class_name,
                                           *constructor_name, arguments);
 }
 
 
 }  // namespace dart