Revert 6ad38498c8673f1fbe3e12c49b1cf590305676dd (PARSED_UNIT).

pkg/analyzer/lib/task/dart.dart

 // Copyright (c) 2015, 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 analyzer.task.dart;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/generated/error.dart';
@@ skipping 66 matching lines @@
 
 /**
  * The fully built [LibraryElement] associated with a library.
  *
  * The result is only available for [Source]s representing a library.
  */
 final ResultDescriptor<LibraryElement> LIBRARY_ELEMENT =
     new ResultDescriptor<LibraryElement>('LIBRARY_ELEMENT', null);
 
 /**
- * The compilation unit AST with resolved [UriBasedDirective]s.
+ * The compilation unit AST produced while parsing a compilation unit.
+ *
+ * The AST structure will not have resolution information associated with it.
  *
  * The result is only available for [Source]s representing a compilation unit.
  */
 final ResultDescriptor<CompilationUnit> PARSED_UNIT =
     new ResultDescriptor<CompilationUnit>('PARSED_UNIT', null,
         cachingPolicy: AST_CACHING_POLICY);
 
 /**
  * The resolved [CompilationUnit] associated with a compilation unit, with
  * constants resolved.
@@ skipping 75 matching lines @@
   @override
   bool operator ==(other) {
     return other is LibrarySpecificUnit &&
         other.library == library &&
         other.unit == unit;
   }
 
   @override
   String toString() => '$unit in $library';
 }