Revert "Adapt and reland old position sticky implementation from https://codereview.chromium.org/34…

third_party/WebKit/Source/core/page/scrolling/StickyPositionScrollingConstraints.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/page/scrolling/StickyPositionScrollingConstraints.h"
-
-namespace blink {
-
-FloatSize StickyPositionScrollingConstraints::computeStickyOffset(const FloatRect& viewportRect) const
-{
-    FloatRect boxRect = m_scrollContainerRelativeStickyBoxRect;
-
-    if (hasAnchorEdge(AnchorEdgeRight)) {
-        float rightLimit = viewportRect.maxX() - m_rightOffset;
-        float rightDelta = std::min<float>(0, rightLimit - m_scrollContainerRelativeStickyBoxRect.maxX());
-        float availableSpace = std::min<float>(0, m_scrollContainerRelativeContainingBlockRect.x() - m_scrollContainerRelativeStickyBoxRect.x());
-        if (rightDelta < availableSpace)
-            rightDelta = availableSpace;
-
-        boxRect.move(rightDelta, 0);
-    }
-
-    if (hasAnchorEdge(AnchorEdgeLeft)) {
-        float leftLimit = viewportRect.x() + m_leftOffset;
-        float leftDelta = std::max<float>(0, leftLimit - m_scrollContainerRelativeStickyBoxRect.x());
-        float availableSpace = std::max<float>(0, m_scrollContainerRelativeContainingBlockRect.maxX() - m_scrollContainerRelativeStickyBoxRect.maxX());
-        if (leftDelta > availableSpace)
-            leftDelta = availableSpace;
-
-        boxRect.move(leftDelta, 0);
-    }
-
-    if (hasAnchorEdge(AnchorEdgeBottom)) {
-        float bottomLimit = viewportRect.maxY() - m_bottomOffset;
-        float bottomDelta = std::min<float>(0, bottomLimit - m_scrollContainerRelativeStickyBoxRect.maxY());
-        float availableSpace = std::min<float>(0, m_scrollContainerRelativeContainingBlockRect.y() - m_scrollContainerRelativeStickyBoxRect.y());
-        if (bottomDelta < availableSpace)
-            bottomDelta = availableSpace;
-
-        boxRect.move(0, bottomDelta);
-    }
-
-    if (hasAnchorEdge(AnchorEdgeTop)) {
-        float topLimit = viewportRect.y() + m_topOffset;
-        float topDelta = std::max<float>(0, topLimit - m_scrollContainerRelativeStickyBoxRect.y());
-        float availableSpace = std::max<float>(0, m_scrollContainerRelativeContainingBlockRect.maxY() - m_scrollContainerRelativeStickyBoxRect.maxY());
-        if (topDelta > availableSpace)
-            topDelta = availableSpace;
-
-        boxRect.move(0, topDelta);
-    }
-
-    return boxRect.location() - m_scrollContainerRelativeStickyBoxRect.location();
-}
-
-} // namespace blink