Use entities in CommonElements interface.

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

 // Copyright (c) 2013, 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.
 
 part of js_backend.backend;
 
 /// For each class, stores the possible class subtype tests that could succeed.
 abstract class TypeChecks {
   /// Get the set of checks required for class [element].
   Iterable<TypeCheck> operator [](ClassElement element);
@@ skipping 247 matching lines @@
     // Add is-checks that result from classes using type variables in checks.
     addImplicitChecks(
         compiler.resolutionWorldBuilder, classesUsingTypeVariableTests);
     // Add the rti dependencies that are implicit in the way the backend
     // generates code: when we create a new [List], we actually create
     // a JSArray in the backend and we need to add type arguments to
     // the calls of the list constructor whenever we determine that
     // JSArray needs type arguments.
     // TODO(karlklose): make this dependency visible from code.
     if (backend.helpers.jsArrayClass != null) {
-      registerRtiDependency(
-          backend.helpers.jsArrayClass, compiler.commonElements.listClass);
+      ClassElement listClass = compiler.commonElements.listClass;
+      registerRtiDependency(backend.helpers.jsArrayClass, listClass);
     }
     // Compute the set of all classes and methods that need runtime type
     // information.
     compiler.resolutionWorldBuilder.isChecks.forEach((ResolutionDartType type) {
       if (type.isInterfaceType) {
         ResolutionInterfaceType itf = type;
         if (!itf.treatAsRaw) {
           potentiallyAddForRti(itf.element);
         }
       } else {
@@ skipping 763 matching lines @@
  * substition for this check.
  */
 class TypeCheck {
   final ClassElement cls;
   final Substitution substitution;
   final int hashCode = _nextHash = (_nextHash + 100003).toUnsigned(30);
   static int _nextHash = 0;
 
   TypeCheck(this.cls, this.substitution);
 }