Move global dependencies to BackendUsage

pkg/compiler/lib/src/js_backend/custom_elements_analysis.dart

Index: pkg/compiler/lib/src/js_backend/custom_elements_analysis.dart
diff --git a/pkg/compiler/lib/src/js_backend/custom_elements_analysis.dart b/pkg/compiler/lib/src/js_backend/custom_elements_analysis.dart
index aacaaee812648e2b8f13f0d344f6a6074913dbcd..9f091a22a95dc93e0c7028439f65fd84c53981c5 100644
--- a/pkg/compiler/lib/src/js_backend/custom_elements_analysis.dart
+++ b/pkg/compiler/lib/src/js_backend/custom_elements_analysis.dart
@@ -173,7 +173,7 @@ class CustomElementsAnalysisJoin {
               .registerStaticUse(new StaticUse.foreignUse(constructor));
         }
         escapingConstructors
-            .forEach(compiler.globalDependencies.registerDependency);
+            .forEach(backend.backendUsage.registerGlobalDependency);
         // Force the generaton of the type constant that is the key to an entry
         // in the generated table.
         ConstantValue constant = makeTypeConstant(classElement);