Use entities in BackendClasses

pkg/compiler/lib/src/inferrer/type_graph_nodes.dart

Index: pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
diff --git a/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart b/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
index 16c92603663bb771dd97fb129ada819c456fe69e..388ee59d4081532d38a35a55242677ea41a4f814 100644
--- a/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
+++ b/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
@@ -870,7 +870,8 @@ class DynamicCallSiteTypeInformation extends CallSiteTypeInformation {
   TypeInformation handleIntrisifiedSelector(
       Selector selector, TypeMask mask, InferrerEngine inferrer) {
     ClosedWorld closedWorld = inferrer.closedWorld;
-    if (!closedWorld.backendClasses.intImplementation.isResolved) return null;
+    ClassElement intClass = closedWorld.backendClasses.intClass;
+    if (!intClass.isResolved) return null;
     if (mask == null) return null;
     if (!mask.containsOnlyInt(closedWorld)) {
       return null;
@@ -879,8 +880,7 @@ class DynamicCallSiteTypeInformation extends CallSiteTypeInformation {
     if (!arguments.named.isEmpty) return null;
     if (arguments.positional.length > 1) return null;
 
-    ClassElement uint31Implementation =
-        closedWorld.backendClasses.uint31Implementation;
+    ClassElement uint31Implementation = closedWorld.backendClasses.uint31Class;
     bool isInt(info) => info.type.containsOnlyInt(closedWorld);
     bool isEmpty(info) => info.type.isEmpty;
     bool isUInt31(info) {
@@ -888,8 +888,8 @@ class DynamicCallSiteTypeInformation extends CallSiteTypeInformation {
     }
 
     bool isPositiveInt(info) {
-      return info.type.satisfies(
-          closedWorld.backendClasses.positiveIntImplementation, closedWorld);
+      return info.type
+          .satisfies(closedWorld.backendClasses.positiveIntClass, closedWorld);
     }
 
     TypeInformation tryLater() => inferrer.types.nonNullEmptyType;