Implement contextmenu attribute with basic support of <menu>

Source/core/html/CustomContextMenuProvider.cpp

+// Copyright 2014 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 "config.h"
+
+#include "core/html/CustomContextMenuProvider.h"
+
+#include "core/html/HTMLMenuElement.h"
+#include "platform/ContextMenu.h"
+
+namespace WebCore {
+
+void CustomContextMenuProvider::populateContextMenu(ContextMenu* menu)
+{
+    for (size_t i = 0; i < m_items.size(); ++i)
+        menu->appendItem(m_items[i]);
+}
+
+void CustomContextMenuProvider::contextMenuItemSelected(const ContextMenuItem* item)
+{
+    if (m_menu) {

[esprehn, 2014/06/20 08:39:57]

Early return instead.

if (!m_menu)
  return;
if (...)
  ...->click();

Also does the spec really say to use the simulated click API like this?

[pals, 2014/06/20 14:22:10]

The spec says " If the command's Action is defined as firing a click event,
either directly or via the run synthetic click activation steps algorithm, then
the relatedTarget attribute of that click event must be initialised to the
subject passed to this construct and show a menu algorithm."

Done.

+        if (HTMLElement* element = m_menu->menuItemAt(item->action()))
+            element->click();
+    }
+}
+
+} // namespace