Move remaining helpers to BackendHelpers

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

Index: pkg/compiler/lib/src/js_backend/runtime_types.dart
diff --git a/pkg/compiler/lib/src/js_backend/runtime_types.dart b/pkg/compiler/lib/src/js_backend/runtime_types.dart
index 7d1c0a4e3c090b266f0a72970d3fb101f7fd1839..849fae3ca01a71298633aa19f7742c1e88d303d8 100644
--- a/pkg/compiler/lib/src/js_backend/runtime_types.dart
+++ b/pkg/compiler/lib/src/js_backend/runtime_types.dart
@@ -264,9 +264,9 @@ class _RuntimeTypes implements RuntimeTypes {
     // the calls of the list constructor whenever we determine that
     // JSArray needs type arguments.
     // TODO(karlklose): make this dependency visible from code.
-    if (backend.jsArrayClass != null) {
+    if (backend.helpers.jsArrayClass != null) {
       registerRtiDependency(
-          backend.jsArrayClass, compiler.coreClasses.listClass);
+          backend.helpers.jsArrayClass, compiler.coreClasses.listClass);
     }
     // Compute the set of all classes and methods that need runtime type
     // information.