Access BackendUsage through ClosedWorld

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 c9925d4e849eb57a1530397512d4868f5e80cf5a..baeb2aa1a46cc89a5f8df54478a8f4efe1c5bad9 100644
--- a/pkg/compiler/lib/src/deferred_load.dart
+++ b/pkg/compiler/lib/src/deferred_load.dart
@@ -34,7 +34,6 @@ import 'elements/elements.dart'
         TypedefElement;
 import 'elements/entities.dart';
 import 'js_backend/js_backend.dart' show JavaScriptBackend;
-import 'js_backend/backend_usage.dart' show BackendUsage;
 import 'resolution/resolution.dart' show AnalyzableElementX;
 import 'resolution/tree_elements.dart' show TreeElements;
 import 'tree/tree.dart' as ast;
@@ -44,6 +43,7 @@ import 'universe/world_impact.dart'
 import 'util/setlet.dart' show Setlet;
 import 'util/uri_extras.dart' as uri_extras;
 import 'util/util.dart' show makeUnique;
+import 'world.dart' show ClosedWorld;
 
 /// A "hunk" of the program that will be loaded whenever one of its [imports]
 /// are loaded.
@@ -162,7 +162,6 @@ class DeferredLoadTask extends CompilerTask {
 
   JavaScriptBackend get backend => compiler.backend;
   DiagnosticReporter get reporter => compiler.reporter;
-  BackendUsage get _backendUsage => backend.backendUsage;
 
   /// Returns the [OutputUnit] where [element] belongs.
   OutputUnit outputUnitForElement(Element element) {
@@ -676,7 +675,7 @@ class DeferredLoadTask extends CompilerTask {
     }
   }
 
-  void onResolutionComplete(FunctionEntity main) {
+  void onResolutionComplete(FunctionEntity main, ClosedWorld closedWorld) {
     if (!isProgramSplit) {
       allOutputUnits.add(mainOutputUnit);
       return;
@@ -700,12 +699,12 @@ class DeferredLoadTask extends CompilerTask {
               // particular element, for example, startRootIsolate.  This set
               // also contains elements for which we lack precise information.
               for (MethodElement element
-                  in _backendUsage.globalFunctionDependencies) {
+                  in closedWorld.backendUsage.globalFunctionDependencies) {
                 _mapDependencies(
                     element: element.implementation, import: _fakeMainImport);
               }
               for (ClassElement element
-                  in _backendUsage.globalClassDependencies) {
+                  in closedWorld.backendUsage.globalClassDependencies) {
                 _mapDependencies(
                     element: element.implementation, import: _fakeMainImport);
               }