Support class and typedef literals as expressions.

lib/compiler/implementation/js_backend/emitter.dart

Index: lib/compiler/implementation/js_backend/emitter.dart
diff --git a/lib/compiler/implementation/js_backend/emitter.dart b/lib/compiler/implementation/js_backend/emitter.dart
index b9d30a3fa4b426e1d5f166bf42e43bd1bf763679..a986c72d7bce8a09e60201116ed34d18d6c6eef5 100644
--- a/lib/compiler/implementation/js_backend/emitter.dart
+++ b/lib/compiler/implementation/js_backend/emitter.dart
@@ -1421,11 +1421,11 @@ $classesCollector.$mangledName = {'':
       String invocationName = "${namer.closureInvocationName(selector)}";
       mainEnsureGetter = "$mainAccess.$invocationName = $mainAccess";
     }
-
     // TODO(ngeoffray): These globals are currently required by the isolate
     // library. They should be removed.
     String runtimeTypeCache =
-        compiler.enabledRuntimeType ? "  context.runtimeTypeCache = {}\n" : "";
+        compiler.needsRuntimeTypeCache() ? "  context.runtimeTypeCache = {}\n"
+                                         : "";
 
     buffer.add("""
 var \$globalThis = $currentIsolate;
@@ -1513,7 +1513,7 @@ if (typeof document != 'undefined' && document.readyState != 'complete') {
       // constants to be set up.
       emitStaticNonFinalFieldInitializations(mainBuffer);
       emitLazilyInitializedStaticFields(mainBuffer);
-      if (compiler.enabledRuntimeType && !compiler.hasIsolateSupport()) {
+      if (compiler.needsRuntimeTypeCache() && !compiler.hasIsolateSupport()) {
         mainBuffer.add('$isolateProperties.runtimeTypeCache = {};\n');
       }