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

pkg/compiler/lib/src/deferred_load.dart

Index: pkg/compiler/lib/src/deferred_load.dart
diff --git a/pkg/compiler/lib/src/deferred_load.dart b/pkg/compiler/lib/src/deferred_load.dart
index f5614d97e15d7437769ce86ec388851b04d1870f..78c0a37a05d5c7751b1355935c7dc62d2aafae28 100644
--- a/pkg/compiler/lib/src/deferred_load.dart
+++ b/pkg/compiler/lib/src/deferred_load.dart
@@ -28,7 +28,6 @@ import 'elements/elements.dart' show
     FunctionElement,
     ImportElement,
     LibraryElement,
-    LocalFunctionElement,
     MetadataAnnotation,
     PrefixElement,
     ScopeContainerElement,
@@ -49,14 +48,11 @@ import 'tree/tree.dart' show
     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;
@@ -126,8 +122,6 @@ class DeferredLoadTask extends CompilerTask {
   /// 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.
   ///
@@ -324,35 +318,30 @@ class DeferredLoadTask extends CompilerTask {
 
         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);