Add support for sync* and yield

runtime/lib/function.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/bootstrap_natives.h"
 
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
@@ skipping 56 matching lines @@
     result += result << 3;
     result ^= result >> 11;
     result += result << 15;
     result &= ((static_cast<intptr_t>(1) << String::kHashBits) - 1);
     return Smi::New(result);
   }
   UNREACHABLE();
   return Object::null();
 }
 
+
+DEFINE_NATIVE_ENTRY(FunctionImpl_clone, 1) {
+  const Instance& receiver = Instance::CheckedHandle(
+      isolate, arguments->NativeArgAt(0));
+  ASSERT(receiver.IsClosure());
+  if (receiver.IsClosure()) {
+    const Function& func =
+        Function::Handle(isolate, Closure::function(receiver));
+    const Context& ctx =
+        Context::Handle(isolate, Closure::context(receiver));
+    Context& cloned_ctx =
+        Context::Handle(isolate, Context::New(ctx.num_variables()));
+    cloned_ctx.set_parent(Context::Handle(isolate, ctx.parent()));
+    Object& inst = Object::Handle(isolate);
+    for (int i = 0; i < ctx.num_variables(); i++) {
+      inst = ctx.At(i);
+      cloned_ctx.SetAt(i, inst);
+    }
+    return Closure::New(func, cloned_ctx);
+  }
+  return Object::null();
+}
+
+
 }  // namespace dart