Block modal dialogs inside sandboxes.

public/web/WebSandboxFlags.h

 // 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.
 
 #ifndef WebSandboxFlags_h
 #define WebSandboxFlags_h
 
 #include "../platform/WebCommon.h"
 
 namespace blink {
 
 // See http://www.whatwg.org/specs/web-apps/current-work/#attr-iframe-sandbox
 // for a list of the sandbox flags.  This enum should be kept in sync with
 // Source/core/dom/SandboxFlags.h.  Enforced in AssertMatchingEnums.cpp
 enum class WebSandboxFlags : int {
     None = 0,
     Navigation = 1,
     Plugins = 1 << 1,
     Origin = 1 << 2,
     Forms = 1 << 3,
     Scripts = 1 << 4,
     TopNavigation = 1 << 5,
     Popups = 1 << 6,
     AutomaticFeatures = 1 << 7,
     PointerLock = 1 << 8,
     DocumentDomain = 1 << 9,
     OrientationLock = 1 << 10,
+    PropagatesToAuxiliaryBrowsingContexts = 1 << 11,
+    Modals = 1 << 12,
     All = -1
 };
 
 } // namespace blink
 
 #endif // WebSandboxFlags_h