Replace LayoutTests/paint/invalidation/text-selection-focus.html with a SimTest.

third_party/WebKit/Source/web/tests/sim/SimPage.cpp

+// Copyright 2016 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 "web/tests/sim/SimPage.h"
+
+#include "core/page/FocusController.h"
+#include "core/page/Page.h"
+
+namespace blink {
+
+SimPage::SimPage() : m_page(nullptr) {}
+
+SimPage::~SimPage() {}
+
+void SimPage::setPage(Page* page) {
+  m_page = page;
+}
+
+void SimPage::setFocused(bool value) {
+  m_page->focusController().setFocused(value);
+}
+
+bool SimPage::isFocused() const {
+  return m_page->focusController().isFocused();
+}
+
+}  // namespace blink