Eliminate all but one top-level class per library.

runtime/lib/mirrors.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 "lib/mirrors.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
@@ skipping 2006 matching lines @@
     if (cls.is_synthesized_class() &&
         !is_typedef &&
         !cls.is_mixin_app_alias() &&
         !cls.is_enum_class()) {
       return Instance::null();  // Synthetic.
     }
     script = cls.script();
     token_pos = cls.token_pos();
   } else if (decl.IsField()) {
     const Field& field = Field::Cast(decl);
-    const Class& owner = Class::Handle(field.owner());
-    script = owner.script();
+    script = field.script();
     token_pos = field.token_pos();
   } else if (decl.IsTypeParameter()) {
     const TypeParameter& type_var = TypeParameter::Cast(decl);
     const Class& owner = Class::Handle(type_var.parameterized_class());
     script = owner.script();
     token_pos = type_var.token_pos();
   } else if (decl.IsLibrary()) {
     const Library& lib = Library::Cast(decl);
     if (lib.raw() == Library::NativeWrappersLibrary()) {
       return Instance::null();  // No source.
@@ skipping 68 matching lines @@
 }
 
 DEFINE_NATIVE_ENTRY(TypeMirror_subtypeTest, 2) {
   GET_NON_NULL_NATIVE_ARGUMENT(AbstractType, a, arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(AbstractType, b, arguments->NativeArgAt(1));
   return Bool::Get(a.IsSubtypeOf(b, NULL)).raw();
 }
 
 
 }  // namespace dart