Remove begin/end subseq. display items, and store on PaintController instead.

third_party/WebKit/Source/core/paint/PaintPropertyTreeUpdateTests.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 "core/html/HTMLIFrameElement.h"
 #include "core/paint/PaintPropertyTreeBuilderTest.h"
 #include "core/paint/PaintPropertyTreePrinter.h"
 
 namespace blink {
 
@@ skipping 128 matching lines @@
       "    background-attachment: fixed;"
       "  }"
       "</style>"
       "<iframe></iframe>"
       "<div id='fixedBackground' class='fixedBackground'></div>"
       "<div id='forceScroll' style='height: 8888px;'></div>");
   setChildFrameHTML(
       "<style>body { margin: 0; }</style>"
       "<div id='forceScroll' style='height: 8888px;'></div>");
   document().view()->updateAllLifecyclePhases();
-
   FrameView* parent = document().view();
   EXPECT_TRUE(frameScroll(parent)->hasBackgroundAttachmentFixedDescendants());
   FrameView* child = childDocument().view();
   EXPECT_TRUE(frameScroll(child)->hasBackgroundAttachmentFixedDescendants());
 
   // Removing a main thread scrolling reason should update the entire tree.
   auto* fixedBackground = document().getElementById("fixedBackground");
   fixedBackground->removeAttribute(HTMLNames::classAttr);
   document().view()->updateAllLifecyclePhases();
   EXPECT_FALSE(frameScroll(parent)->hasBackgroundAttachmentFixedDescendants());
@@ skipping 573 matching lines @@
   EXPECT_TRUE(transform->flattensInheritedTransform());
 
   document().getElementById("parent")->setAttribute(
       HTMLNames::styleAttr, "transform-style: preserve-3d");
   document().view()->updateAllLifecyclePhases();
   EXPECT_EQ(transform, child->paintProperties()->transform());
   EXPECT_FALSE(transform->flattensInheritedTransform());
 }
 
 }  // namespace blink