Implement the invoke methods (invoke, getField, setField, newInstance, apply) as internal natives.

runtime/vm/dart_entry.h

Index: runtime/vm/dart_entry.h
===================================================================
--- runtime/vm/dart_entry.h	(revision 25019)
+++ runtime/vm/dart_entry.h	(working copy)
@@ -142,6 +142,13 @@
                                        const String& target_name,
                                        const Array& arguments,
                                        const Array& arguments_descriptor);
+
+  // Invokes a generative constructor, redirecting constructor, factory or
+  // redirecting factory. On success, returns a RawInstance. On failure,
+  // a RawError.
+  static RawObject* InvokeConstructor(const Class& klass,
+                                      const Function &constructor,
+                                      const Array& arguments);
 };