Move definition of Feature next to definitions of WorldImpact and Use

pkg/compiler/lib/src/universe/world_impact.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 dart2js.universe.world_impact;
 
 import '../elements/elements.dart' show Element;
 import '../util/util.dart' show Setlet;
 import 'use.dart' show DynamicUse, StaticUse, TypeUse;
 
+/// Describes of how an element (e.g. a method) impacts the closed-world

[Harry Terkelsen, 2016/08/16 19:36:13]

Either delete "of" or change Describes to Description

[Siggi Cherem (dart-lang), 2016/08/16 19:43:30]

Done.

+/// semantics of a program.
+///
+/// A [WorldImpact] contains information about how a program element affects our
+/// understanding of what's live in a program. For example, it can indicate
+/// that a method uses certain feature, or allocates a specific type.

[Harry Terkelsen, 2016/08/16 19:36:13]

"uses a certain feature"

[Siggi Cherem (dart-lang), 2016/08/16 19:43:30]

Done.

+///
+/// The impact object can be computed locally by inspecting just the resolution
+/// information of that element alone. The compiler uses [Universe] and
+/// [ClassWorld] to combine the information discoverred in the impact objects of

[Harry Terkelsen, 2016/08/16 19:36:13]

discovered

[Siggi Cherem (dart-lang), 2016/08/16 19:43:30]

Done.

+/// all elements reachable in an application.
 class WorldImpact {
   const WorldImpact();
 
   Iterable<DynamicUse> get dynamicUses => const <DynamicUse>[];
 
   Iterable<StaticUse> get staticUses => const <StaticUse>[];
 
   // TODO(johnniwinther): Replace this by called constructors with type
   // arguments.
   // TODO(johnniwinther): Collect all checked types for checked mode separately
@@ skipping 201 matching lines @@
     }
   }
 
   @override
   void visitTypeUse(TypeUse use) {
     if (_visitTypeUse != null) {
       _visitTypeUse(use);
     }
   }
 }