Move global dependencies to BackendUsage

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/tasks.dart' show CompilerTask;
 import 'common.dart';
 import 'compiler.dart' show Compiler;
 import 'constants/expressions.dart' show ConstantExpression;
@@ skipping 662 matching lines @@
         () => measure(() {
               // Starting from main, traverse the program and find all
               // dependencies.
               _mapDependencies(
                   element: compiler.mainFunction, import: _fakeMainImport);
 
               // Also add "global" dependencies to the main OutputUnit.  These
               // are things that the backend needs but cannot associate with a
               // particular element, for example, startRootIsolate.  This set
               // also contains elements for which we lack precise information.
-              for (Element element
-                  in compiler.globalDependencies.otherDependencies) {
+              for (Element element in backend.backendUsage.globalDependencies) {
                 _mapDependencies(element: element, import: _fakeMainImport);
               }
 
               // Now check to see if we have to add more elements due to
               // mirrors.
               if (compiler.commonElements.mirrorsLibrary != null) {
                 _addMirrorElements();
               }
 
               // Build the OutputUnits using these two maps.
@@ skipping 356 matching lines @@
 
   bool operator ==(other) {
     if (other is! _DeclaredDeferredImport) return false;
     return declaration == other.declaration;
   }
 
   int get hashCode => declaration.hashCode * 17;
 
   String toString() => '$declaration';
 }