cps-ir: Set runtime type information for new objects that require it.

pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart

Index: pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
diff --git a/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart b/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
index 150825934948c6bf2e08de0197ab074d3698f5af..81c6ea37a02b8e05199b1b9fe7f2d29f1511de93 100644
--- a/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
+++ b/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
@@ -937,6 +937,11 @@ class ASTEmitter
   }
 
   @override
+  Expression visitTypeExpression(tree.TypeExpression node, arg) {
+    throw '$node not supported by dart backend';
+  }
+
+  @override
   visitGetField(tree.GetField node, arg) => errorUnsupportedNode(node);
 
   @override
@@ -963,6 +968,7 @@ class ASTEmitter
   errorUnsupportedNode(tree.JsSpecificNode node) {
     throw '$node not supported by dart backend';
   }
+
 }
 
 class TypeGenerator {