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

tests/compiler/dart2js/world_test.dart

Index: tests/compiler/dart2js/world_test.dart
diff --git a/tests/compiler/dart2js/world_test.dart b/tests/compiler/dart2js/world_test.dart
index 0109f8d5b9d575741b4a8ead8843bf4803510569..ee0bfdaf5c52715e9665b8c9c40a8824c141d84c 100644
--- a/tests/compiler/dart2js/world_test.dart
+++ b/tests/compiler/dart2js/world_test.dart
@@ -44,7 +44,7 @@ testClassSets() async {
       }
       """,
       useMockCompiler: false);
-  ClassWorld classWorld = env.compiler.world;
+  ClassWorld classWorld = env.compiler.closedWorld;
 
   ClassElement Object_ = env.getElement("Object");
   ClassElement A = env.getElement("A");
@@ -67,14 +67,14 @@ testClassSets() async {
       Expect.isTrue(foundClasses.contains(expectedClass),
           "Expect $expectedClass in '$property' on $cls. "
           "Found:\n ${foundClasses.join('\n ')}\n"
-          "${env.compiler.world.dump(cls)}");
+          "${env.compiler.closedWorld.dump(cls)}");
     }
     if (exact) {
       Expect.equals(expectedClasses.length, foundClasses.length,
           "Unexpected classes "
           "${foundClasses.where((c) => !expectedClasses.contains(c))} "
           "in '$property' on $cls.\n"
-          "${env.compiler.world.dump(cls)}");
+          "${env.compiler.closedWorld.dump(cls)}");
     }
   }
 
@@ -101,7 +101,7 @@ testClassSets() async {
       int count = getCount(cls);
       Expect.equals(expectedClasses.length, count,
           "Unexpected class count in '$property' on $cls.\n"
-          "${env.compiler.world.dump(cls)}");
+          "${env.compiler.closedWorld.dump(cls)}");
     }
 
   }
@@ -257,7 +257,7 @@ testProperties() async {
       }
       """,
       useMockCompiler: false);
-  ClassWorld classWorld = env.compiler.world;
+  ClassWorld classWorld = env.compiler.closedWorld;
 
   check(String name,
       {bool hasStrictSubtype,