Make closedWorld a property of ClosedWorldRefiner.

pkg/compiler/lib/src/compiler.dart

Index: pkg/compiler/lib/src/compiler.dart
diff --git a/pkg/compiler/lib/src/compiler.dart b/pkg/compiler/lib/src/compiler.dart
index 9670004de3495b9d97bbcbbc26218d6c84964481..b4ee8bcdb119144aa637cc39d754b6dc3f64b12a 100644
--- a/pkg/compiler/lib/src/compiler.dart
+++ b/pkg/compiler/lib/src/compiler.dart
@@ -691,9 +691,7 @@ abstract class Compiler implements LibraryLoaderListener {
         assert(mainFunction != null);
 
         ClosedWorldRefiner closedWorldRefiner = closeResolution();
-        // TODO(johnniwinther): Make [ClosedWorld] a property of
-        // [ClosedWorldRefiner].
-        ClosedWorld closedWorld = resolverWorld.closedWorldForTesting;
+        ClosedWorld closedWorld = closedWorldRefiner.closedWorld;
 
         reporter.log('Inferring types...');
         globalInference.runGlobalTypeInference(
@@ -706,6 +704,7 @@ abstract class Compiler implements LibraryLoaderListener {
         reporter.log('Compiling...');
         phase = PHASE_COMPILING;
 
+        codegenWorld.open(closedWorld);
         enqueuer.codegen.applyImpact(backend.onCodegenStart(closedWorld));
         if (compileAll) {
           libraryLoader.libraries.forEach((LibraryElement library) {