Revert "Remove WorldImpact from caches when no longer needed."

pkg/compiler/lib/src/deferred_load.dart

 // Copyright (c) 2014, 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 deferred_load;
 
 import 'common.dart';
 import 'common/backend_api.dart' show
     Backend;
 import 'common/tasks.dart' show
@@ skipping 10 matching lines @@
     AccessorElement,
     AstElement,
     ClassElement,
     Element,
     ElementKind,
     Elements,
     ExportElement,
     FunctionElement,
     ImportElement,
     LibraryElement,
-    LocalFunctionElement,
     MetadataAnnotation,
     PrefixElement,
     ScopeContainerElement,
     TypedefElement;
 import 'js_backend/js_backend.dart' show
     JavaScriptBackend;
 import 'resolution/resolution.dart' show
     AnalyzableElementX;
 import 'resolution/tree_elements.dart' show
     TreeElements;
 import 'tree/tree.dart' as ast;
 import 'tree/tree.dart' show
     Import,
     LibraryTag,
     LibraryDependency,
     LiteralDartString,
     LiteralString,
     NewExpression,
     Node;
 import 'universe/use.dart' show
-    DynamicUse,
     StaticUse,
     TypeUse,
     TypeUseKind;
 import 'universe/world_impact.dart' show
-    ImpactUseCase,
-    WorldImpact,
-    WorldImpactVisitorImpl;
+    WorldImpact;
 import 'util/setlet.dart' show
     Setlet;
 import 'util/uri_extras.dart' as uri_extras;
 import 'util/util.dart' show
     Link, makeUnique;
 
 /// A "hunk" of the program that will be loaded whenever one of its [imports]
 /// are loaded.
 ///
 /// Elements that are only used in one deferred import, is in an OutputUnit with
@@ skipping 49 matching lines @@
   /// The OutputUnit that will be loaded when the program starts.
   final OutputUnit mainOutputUnit = new OutputUnit(isMainOutput: true);
 
   /// A set containing (eventually) all output units that will result from the
   /// program.
   final Set<OutputUnit> allOutputUnits = new Set<OutputUnit>();
 
   /// Will be `true` if the program contains deferred libraries.
   bool isProgramSplit = false;
 
-  static const ImpactUseCase IMPACT_USE = const ImpactUseCase('Deferred load');
-
   /// A mapping from the name of a defer import to all the output units it
   /// depends on in a list of lists to be loaded in the order they appear.
   ///
   /// For example {"lib1": [[lib1_lib2_lib3], [lib1_lib2, lib1_lib3],
   /// [lib1]]} would mean that in order to load "lib1" first the hunk
   /// lib1_lib2_lib2 should be loaded, then the hunks lib1_lib2 and lib1_lib3
   /// can be loaded in parallel. And finally lib1 can be loaded.
   final Map<String, List<OutputUnit>> hunksToLoad =
       new Map<String, List<OutputUnit>>();
 
@@ skipping 176 matching lines @@
       } else {
         // TODO(sigurdm): We want to be more specific about this - need a better
         // way to query "liveness".
         AstElement analyzableElement = element.analyzableElement.declaration;
         if (!compiler.enqueuer.resolution.hasBeenProcessed(analyzableElement)) {
           return;
         }
 
         WorldImpact worldImpact =
             compiler.resolution.getWorldImpact(analyzableElement);
-        compiler.impactStrategy.visitImpact(
-            analyzableElement,
-            worldImpact,
-            new WorldImpactVisitorImpl(
-                visitStaticUse: (StaticUse staticUse) {
-                  elements.add(staticUse.element);
-                },
-                visitTypeUse: (TypeUse typeUse) {
-                  DartType type = typeUse.type;
-                  switch (typeUse.kind) {
-                    case TypeUseKind.TYPE_LITERAL:
-                      if (type.isTypedef || type.isInterfaceType) {
-                        elements.add(type.element);
-                      }
-                      break;
-                    case TypeUseKind.INSTANTIATION:
-                    case TypeUseKind.IS_CHECK:
-                    case TypeUseKind.AS_CAST:
-                    case TypeUseKind.CATCH_TYPE:
-                      collectTypeDependencies(type);
-                      break;
-                    case TypeUseKind.CHECKED_MODE_CHECK:
-                      if (compiler.enableTypeAssertions) {
-                        collectTypeDependencies(type);
-                      }
-                      break;
-                  }
-                }),
-             IMPACT_USE);
+        worldImpact.staticUses.forEach((StaticUse staticUse) {
+          elements.add(staticUse.element);
+        });
+        for (TypeUse typeUse in worldImpact.typeUses) {
+          DartType type = typeUse.type;
+          switch (typeUse.kind) {
+            case TypeUseKind.TYPE_LITERAL:
+              if (type.isTypedef || type.isInterfaceType) {
+                elements.add(type.element);
+              }
+              break;
+            case TypeUseKind.INSTANTIATION:
+            case TypeUseKind.IS_CHECK:
+            case TypeUseKind.AS_CAST:
+            case TypeUseKind.CATCH_TYPE:
+              collectTypeDependencies(type);
+              break;
+            case TypeUseKind.CHECKED_MODE_CHECK:
+              if (compiler.enableTypeAssertions) {
+                collectTypeDependencies(type);
+              }
+              break;
+          }
+        }
 
         TreeElements treeElements = analyzableElement.resolvedAst.elements;
         assert(treeElements != null);
 
         treeElements.forEachConstantNode((Node node, _) {
           // Explicitly depend on the backend constants.
           ConstantValue value =
               backend.constants.getConstantValueForNode(node, treeElements);
           if (value != null) {
             // TODO(johnniwinther): Assert that all constants have values when
@@ skipping 643 matching lines @@
     return result;
   }
 
   bool operator ==(other) {
     if (other is! _DeclaredDeferredImport) return false;
     return declaration == other.declaration;
   }
 
   int get hashCode => declaration.hashCode * 17;
 }