Ensure libraries always have at least one top-level class and therefore at least one script.

runtime/vm/object.cc

 // Copyright (c) 2012, 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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 9625 matching lines @@
 }
 
 
 RawObject* Library::Evaluate(const String& expr,
                              const Array& param_names,
                              const Array& param_values) const {
   // Take or make a fake top-level class and evaluate the expression
   // as a static function of the class.
   Class& top_level_class = Class::Handle();
   Array& top_level_classes = Array::Handle(anonymous_classes());
-  if (top_level_classes.Length() > 0) {
-    top_level_class ^= top_level_classes.At(0);
-  } else {
-    // A library may have no top-level classes if it has no top-level
-    // variables or methods.
-    Script& script = Script::Handle(Script::New(Symbols::Empty(),
-                                                Symbols::Empty(),
-                                                RawScript::kSourceTag));
-    top_level_class = Class::New(Symbols::TopLevel(), script, 0);
-    top_level_class.set_is_finalized();
-    top_level_class.set_library(*this);
-    AddAnonymousClass(top_level_class);
-  }
+  ASSERT(top_level_classes.Length() > 0);
+  top_level_class ^= top_level_classes.At(0);
   ASSERT(top_level_class.is_finalized());
   return top_level_class.Evaluate(expr, param_names, param_values);
 }
 
 
 void Library::InitNativeWrappersLibrary(Isolate* isolate) {
   static const int kNumNativeWrappersClasses = 4;
   ASSERT(kNumNativeWrappersClasses > 0 && kNumNativeWrappersClasses < 10);
   const String& native_flds_lib_url = Symbols::DartNativeWrappers();
   const Library& native_flds_lib = Library::Handle(
@@ skipping 11072 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart