Redo "Information about which functions require other functions is gathered in the enqueuer."

sdk/lib/_internal/compiler/implementation/common.dart

 // Copyright (c) 2013, 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.
 
 library dart2js.common;
 
 export 'dart2jslib.dart' show
     CompilerTask,
     Compiler,
     Constant,
     ConstantEnvironment,
     InterceptorConstant,
     MessageKind,
     NullConstant,
     Selector,
     TreeElements,
     TypeConstant,
     invariant;
 
 export 'dart_types.dart' show
     DartType,
     FunctionType,
     InterfaceType,
     TypeVariableType,
     Types;
 
 export 'elements/elements.dart' show
     ClassElement,
     ClosureFieldElement,
+    CompilationUnitElement,
     Element,
     Elements,
     FunctionElement,
     FunctionSignature,
     LibraryElement,
     MetadataAnnotation,
     MixinApplicationElement,
     TypedefElement,
     VariableElement;
 
 export 'tree/tree.dart' show
     Node;
 
 export 'types/types.dart' show
     TypeMask;
 
 export 'universe/universe.dart' show
     SelectorKind;
 
 export 'util/util.dart' show
     Link,
     SpannableAssertionFailure;