Generative constructor factories for native objects

sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart

Index: sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart b/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
index 8d0c6a9bdcd39808fd44a6ceef4e6769a9975993..7a457526093ac65dafe2d90c24c29f5fac190b27 100644
--- a/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
@@ -2967,6 +2967,25 @@ class CodeEmitterTask extends CompilerTask {
           ClassElement classElement = element;
           elements.add(backend.emitter.constantReference(constant));
           elements.add(js(namer.isolateAccess(classElement)));
+
+          // Create JavaScript Object map for by-name lookup of generative
+          // constructors.
+          var properties = [];
+          classElement.forEachMember(
+              (ClassElement enclosingClass, Element member) {
+                if (member.isGenerativeConstructor()) {
+                  properties.add(
+                      new jsAst.Property(
+                          js.string(member.name.slowToString()),
+                          new jsAst.VariableUse(
+                              backend.namer.isolateAccess(member))));
+                }
+              },
+              includeBackendMembers: false,
+              includeSuperAndInjectedMembers: false);
+
+          var map = new jsAst.ObjectInitializer(properties);
+          elements.add(map);
         }
       }
     }