First pass at removing position:fixed.

sky/engine/core/rendering/RenderBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 1538 matching lines @@
             offset += layer()->offsetForInFlowPosition();
         transformState.move(offset);
         return;
     }
 
     bool containerSkipped;
     RenderObject* o = container(paintInvalidationContainer, &containerSkipped);
     if (!o)
         return;
 
-    bool isFixedPos = style()->position() == FixedPosition;
     bool hasTransform = hasLayer() && layer()->transform();
     // If this box has a transform, it acts as a fixed position container for fixed descendants,
     // and may itself also be fixed position. So propagate 'fixed' up only if this box is fixed position.
-    if (hasTransform && !isFixedPos)
+    if (hasTransform)
         mode &= ~IsFixed;
-    else if (isFixedPos)
-        mode |= IsFixed;
 
     if (wasFixed)
         *wasFixed = mode & IsFixed;
 
     LayoutSize containerOffset = offsetFromContainer(o, roundedLayoutPoint(transformState.mappedPoint()));
 
     bool preserve3D = mode & UseTransforms && (o->style()->preserves3D() || style()->preserves3D());
     if (mode & UseTransforms && shouldUseTransformFromContainer(o)) {
         TransformationMatrix t;
         getTransformFromContainer(o, containerOffset, t);
         transformState.applyTransform(t, preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
     } else
         transformState.move(containerOffset.width(), containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
 
     if (containerSkipped) {
         // There can't be a transform between paintInvalidationContainer and o, because transforms create containers, so it should be safe
         // to just subtract the delta between the paintInvalidationContainer and o.
         LayoutSize containerOffset = paintInvalidationContainer->offsetFromAncestorContainer(o);
         transformState.move(-containerOffset.width(), -containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
         return;
     }
 
     mode &= ~ApplyContainerFlip;
 
     o->mapLocalToContainer(paintInvalidationContainer, transformState, mode, wasFixed);
 }
 
 void RenderBox::mapAbsoluteToLocalPoint(MapCoordinatesFlags mode, TransformState& transformState) const
 {
-    bool isFixedPos = style()->position() == FixedPosition;
     bool hasTransform = hasLayer() && layer()->transform();
-    if (hasTransform && !isFixedPos) {
+    if (hasTransform) {
         // If this box has a transform, it acts as a fixed position container for fixed descendants,
         // and may itself also be fixed position. So propagate 'fixed' up only if this box is fixed position.
         mode &= ~IsFixed;
-    } else if (isFixedPos)
-        mode |= IsFixed;
+    }
 
     RenderBoxModelObject::mapAbsoluteToLocalPoint(mode, transformState);
 }
 
 LayoutSize RenderBox::offsetFromContainer(const RenderObject* o, const LayoutPoint& point, bool* offsetDependsOnPoint) const
 {
     ASSERT(o == container());
 
     LayoutSize offset;
     if (isRelPositioned())
@@ skipping 105 matching lines @@
     // physical coordinate space of the paintInvalidationContainer.
     RenderStyle* styleToUse = style();
 
     EPosition position = styleToUse->position();
 
     // We need to inflate the paint invalidation rect before we use paintInvalidationState,
     // else we would forget to inflate it for the current renderer. FIXME: If these were
     // included into the visual overflow for repaint, we wouldn't have this issue.
     inflatePaintInvalidationRectForReflectionAndFilter(rect);
 
-    if (paintInvalidationState && paintInvalidationState->canMapToContainer(paintInvalidationContainer) && position != FixedPosition) {
+    if (paintInvalidationState && paintInvalidationState->canMapToContainer(paintInvalidationContainer)) {
         if (layer() && layer()->transform())
             rect = layer()->transform()->mapRect(pixelSnappedIntRect(rect));
 
         // We can't trust the bits on RenderObject, because this might be called while re-resolving style.
         if (styleToUse->hasInFlowPosition() && layer())
             rect.move(layer()->offsetForInFlowPosition());
 
         rect.moveBy(location());
         rect.move(paintInvalidationState->paintOffset());
         if (paintInvalidationState->isClipped())
@@ skipping 708 matching lines @@
     // See http://www.w3.org/TR/2014/CR-css-writing-modes-3-20140320/#orthogonal-flows
     containingBlock->setMarginBeforeForChild(this, marginBefore);
     containingBlock->setMarginAfterForChild(this, marginAfter);
 }
 
 LayoutUnit RenderBox::containingBlockLogicalWidthForPositioned(const RenderBoxModelObject* containingBlock, bool checkForPerpendicularWritingMode) const
 {
     if (checkForPerpendicularWritingMode && containingBlock->isHorizontalWritingMode() != isHorizontalWritingMode())
         return containingBlockLogicalHeightForPositioned(containingBlock, false);
 
-    // Use viewport as container for top-level fixed-position elements.
-    if (style()->position() == FixedPosition && containingBlock->isRenderView()) {
-        const RenderView* view = toRenderView(containingBlock);
-        if (FrameView* frameView = view->frameView()) {
-            LayoutRect viewportRect = frameView->visibleContentRect();
-            return containingBlock->isHorizontalWritingMode() ? viewportRect.width() : viewportRect.height();
-        }
-    }
-
     if (containingBlock->isBox())
         return toRenderBox(containingBlock)->clientLogicalWidth();
 
     ASSERT(containingBlock->isRenderInline() && containingBlock->isRelPositioned());
 
     const RenderInline* flow = toRenderInline(containingBlock);
     InlineFlowBox* first = flow->firstLineBox();
     InlineFlowBox* last = flow->lastLineBox();
 
     // If the containing block is empty, return a width of 0.
@@ skipping 11 matching lines @@
     }
 
     return std::max<LayoutUnit>(0, fromRight - fromLeft);
 }
 
 LayoutUnit RenderBox::containingBlockLogicalHeightForPositioned(const RenderBoxModelObject* containingBlock, bool checkForPerpendicularWritingMode) const
 {
     if (checkForPerpendicularWritingMode && containingBlock->isHorizontalWritingMode() != isHorizontalWritingMode())
         return containingBlockLogicalWidthForPositioned(containingBlock, false);
 
-    // Use viewport as container for top-level fixed-position elements.
-    if (style()->position() == FixedPosition && containingBlock->isRenderView()) {
-        const RenderView* view = toRenderView(containingBlock);
-        if (FrameView* frameView = view->frameView()) {
-            LayoutRect viewportRect = frameView->visibleContentRect();
-            return containingBlock->isHorizontalWritingMode() ? viewportRect.height() : viewportRect.width();
-        }
-    }
-
     if (containingBlock->isBox()) {
         const RenderBlock* cb = containingBlock->isRenderBlock() ?
             toRenderBlock(containingBlock) : containingBlock->containingBlock();
         return cb->clientLogicalHeight();
     }
 
     ASSERT(containingBlock->isRenderInline() && containingBlock->isRelPositioned());
 
     const RenderInline* flow = toRenderInline(containingBlock);
     InlineFlowBox* first = flow->firstLineBox();
@@ skipping 1691 matching lines @@
 
 RenderBox::BoxDecorationData::BoxDecorationData(const RenderStyle& style)
 {
     backgroundColor = style.colorIncludingFallback(CSSPropertyBackgroundColor);
     hasBackground = backgroundColor.alpha() || style.hasBackgroundImage();
     ASSERT(hasBackground == style.hasBackground());
     hasBorder = style.hasBorder();
 }
 
 } // namespace blink