Split World usage into open, inference, and closed world.

tests/compiler/dart2js/serialization/model_test_helper.dart

Index: tests/compiler/dart2js/serialization/model_test_helper.dart
diff --git a/tests/compiler/dart2js/serialization/model_test_helper.dart b/tests/compiler/dart2js/serialization/model_test_helper.dart
index ef923035d4cbfb605dd824b4805eb167b554a23f..bde047ba53ed956ae6c956ffd68da54f99e44607 100644
--- a/tests/compiler/dart2js/serialization/model_test_helper.dart
+++ b/tests/compiler/dart2js/serialization/model_test_helper.dart
@@ -77,7 +77,7 @@ Future checkModels(
     compilerNormal.resolution.retainCachesForTesting = true;
     await compilerNormal.run(entryPoint);
     compilerNormal.phase = Compiler.PHASE_DONE_RESOLVING;
-    compilerNormal.world.populate();
+    compilerNormal.openWorld.populate();
     compilerNormal.backend.onResolutionComplete();
     compilerNormal.deferredLoadTask.onResolutionComplete(
         compilerNormal.mainFunction);
@@ -93,7 +93,7 @@ Future checkModels(
     compilerDeserialized.resolution.retainCachesForTesting = true;
     await compilerDeserialized.run(entryPoint);
     compilerDeserialized.phase = Compiler.PHASE_DONE_RESOLVING;
-    compilerDeserialized.world.populate();
+    compilerDeserialized.openWorld.populate();
     compilerDeserialized.backend.onResolutionComplete();
     compilerDeserialized.deferredLoadTask.onResolutionComplete(
         compilerDeserialized.mainFunction);
@@ -140,9 +140,9 @@ Future checkModels(
     checkClassHierarchyNodes(
         compilerNormal,
         compilerDeserialized,
-        compilerNormal.world.getClassHierarchyNode(
+        compilerNormal.closedWorld.getClassHierarchyNode(
             compilerNormal.coreClasses.objectClass),
-        compilerDeserialized.world.getClassHierarchyNode(
+        compilerDeserialized.closedWorld.getClassHierarchyNode(
             compilerDeserialized.coreClasses.objectClass),
         verbose: verbose);
 
@@ -286,8 +286,8 @@ void checkMixinUses(
     {bool verbose: false}) {
 
   checkSets(
-      compiler1.world.mixinUsesOf(class1),
-      compiler2.world.mixinUsesOf(class2),
+      compiler1.closedWorld.mixinUsesOf(class1),
+      compiler2.closedWorld.mixinUsesOf(class2),
       "Mixin uses of $class1 vs $class2",
       areElementsEquivalent,
       verbose: verbose);
@@ -331,9 +331,9 @@ void checkClassHierarchyNodes(
       if (child.isInstantiated) {
         print('Missing subclass ${child.cls} of ${node1.cls} '
             'in ${node2.directSubclasses}');
-        print(compiler1.world.dump(
+        print(compiler1.closedWorld.dump(
             verbose ? compiler1.coreClasses.objectClass : node1.cls));
-        print(compiler2.world.dump(
+        print(compiler2.closedWorld.dump(
             verbose ? compiler2.coreClasses.objectClass : node2.cls));
       }
       Expect.isFalse(child.isInstantiated,