https://bugs.webkit.org/show_bug.cgi?id=116296

Reviewed by David Hyatt.

Source/WebCore:

The patch extends the region ranges implementation with the following behavior:
- the range of a box is always included in the range of its containing block (even for floats); this will simplify how overflow
is propagated to the regions and it should later change on a case by case basis.
- if the range of a box is not correctly estimated before the layout it will be marked for relayout; this is necessary to correctly
position boxes that overflow naturally, like floats.
- all the boxes have a range now, not only the blocks.
- regionAtBlockOffset can clamp to a box.
- an unsplittable box has a region range of a single region, the one where the box top falls into.

When the layout of a child box starts it tries to give an estimate based on the maximal height of the box. After the layout,
if the estimation was wrong, the box is relaid out. For example, if a block with a float is laid out in a region but the float
overflows in the next region a relayout is needed for the float so it can be positioned relative to the containing block
region (this step can be optimized by making a layout pass only for the children that don't have the region range enclosed in the
containing block range).

Tests: fast/regions/bottom-overflow-out-of-first-region-absolute.html
       fast/regions/float-pushed-width-change-2.html
       fast/regions/scrollable-paragraph-unsplittable.html

* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::updateShapesBeforeBlockLayout): Doesn't do anything for regions now.
(WebCore::RenderBlock::updateShapesAfterBlockLayout): Doesn't do anything for regions now.
(WebCore::RenderBlock::relayoutToAvoidWidows): The layout to avoid widows. Widows use the line index to determine the break point,
not the RootLineBox pointer as before. This is necessary to prevent stale pointers in further layouts.
(WebCore::RenderBlock::layoutBlock):
(WebCore::RenderBlock::layoutBlockChild):
(WebCore::RenderBlock::layoutPositionedObjects):
(WebCore::RenderBlock::markForPaginationRelayoutIfNeeded): Relayout for widows during layoutBlock(). Don't wait to exit the block layout.
(WebCore::RenderBlock::positionNewFloats):
(WebCore::RenderBlock::hasNextPage):
(WebCore::RenderBlock::applyBeforeBreak):
(WebCore::RenderBlock::applyAfterBreak):
(WebCore::RenderBlock::setPageBreak):
(WebCore::RenderBlock::updateMinimumPageHeight):
(WebCore::RenderBlock::regionAtBlockOffset): This function can now clamp at a box.
(WebCore::RenderBlock::computeRegionRangeForBoxChild): Calculate the box region range using the box height.
(WebCore::RenderBlock::estimateRegionRangeForBoxChild): Estimate the box region range using a huge height for the box.
(WebCore::RenderBlock::updateRegionRangeForBoxChild): Determine the final region range of a box.
* rendering/RenderBlock.h:
(WebCore::RenderBlock::logicalWidthForChild):
(WebCore::RenderBlock::logicalHeightForChild):
(WebCore::RenderBlock::logicalTopForChild):
* rendering/RenderBlockLineLayout.cpp:
(WebCore::RenderBlock::layoutInlineChildren):
* rendering/RenderBox.cpp:
(WebCore::RenderBox::clampToStartAndEndRegions):
(WebCore::RenderBox::borderBoxRectInRegion):
* rendering/RenderBox.h:
* rendering/RenderDeprecatedFlexibleBox.cpp:
(WebCore::RenderDeprecatedFlexibleBox::layoutBlock):
* rendering/RenderFlexibleBox.cpp:
(WebCore::RenderFlexibleBox::layoutBlock):
* rendering/RenderFlowThread.cpp:
(WebCore::RenderFlowThread::validateRegions):
(WebCore::RenderFlowThread::regionAtBlockOffset):
(WebCore::RenderFlowThread::adjustedPositionRelativeToOffsetParent):
(WebCore::RenderFlowThread::pageLogicalTopForOffset):
(WebCore::RenderFlowThread::pageLogicalWidthForOffset):
(WebCore::RenderFlowThread::pageLogicalHeightForOffset):
(WebCore::RenderFlowThread::pageRemainingLogicalHeightForOffset):
(WebCore::RenderFlowThread::mapFromFlowToRegion):
(WebCore::RenderFlowThread::logicalWidthChangedInRegionsForBlock):
(WebCore::RenderFlowThread::clearRenderObjectCustomStyle):
(WebCore::RenderFlowThread::clearRenderBoxRegionInfoAndCustomStyle):
(WebCore::RenderFlowThread::setRegionRangeForBox):
(WebCore::RenderFlowThread::applyBreakAfterContent):
(WebCore::RenderFlowThread::addForcedRegionBreak):
* rendering/RenderFlowThread.h:
* rendering/RenderGrid.cpp:
(WebCore::RenderGrid::layoutBlock):
* rendering/RenderMultiColumnFlowThread.cpp:
(WebCore::RenderMultiColumnFlowThread::setPageBreak):
(WebCore::RenderMultiColumnFlowThread::updateMinimumPageHeight):
* rendering/RenderMultiColumnFlowThread.h:

LayoutTests:

Tests for the changes in how region ranges are computed and applied.

* fast/regions/bottom-overflow-out-of-first-region-absolute-expected.html: Added.
* fast/regions/bottom-overflow-out-of-first-region-absolute.html: Added.
* fast/regions/float-pushed-width-change-2-expected.html: Copied from LayoutTests/fast/regions/float-pushed-width-change-expected.html.
* fast/regions/float-pushed-width-change-2.html: Copied from LayoutTests/fast/regions/float-pushed-width-change.html.
* fast/regions/float-pushed-width-change-expected.html:
* fast/regions/float-pushed-width-change.html:
* fast/regions/scrollable-paragraph-unsplittable-expected.html: Added.
* fast/regions/scrollable-paragraph-unsplittable.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@153990 268f45cc-cd09-0410-ab3c-d52691b4dbfc