Add dart_invoke to tonic for calls into App code.

sky/engine/tonic/dart_invoke.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "sky/engine/config.h"
+#include "sky/engine/tonic/dart_invoke.h"
+
+#include "base/logging.h"
+#include "base/trace_event/trace_event.h"
+#include "sky/engine/tonic/dart_error.h"
+
+namespace blink {
+
+bool DartInvokeNamedAppClosure(Dart_Handle target, Dart_Handle name,

[abarth-chromium, 2015/02/24 19:28:20]

Maybe DartInvokeApp for consistency with the DartVM API?

+                               int number_of_arguments,
+                               Dart_Handle* arguments) {
+  TRACE_EVENT0("sky", "DartInvoke::DartInvokeNamedAppClosure");
+  return LogIfError(Dart_Invoke(target, name, number_of_arguments, arguments));
+}
+
+bool DartInvokeAppClosure(Dart_Handle closure,
+                          int number_of_arguments,
+                          Dart_Handle* arguments) {
+  TRACE_EVENT0("sky", "DartInvoke::DartInvokeAppClosure");
+  return LogIfError(
+      Dart_InvokeClosure(closure, number_of_arguments, arguments));
+}
+
+}  // namespace blink