Source/WebCore: https://bugs.webkit.org/show_bug.cgi?id=76197

Source/WebCore: https://bugs.webkit.org/show_bug.cgi?id=76197

Implementation of baseline grid alignment. This patch implements line grid tracking in the layout state,
and also implements the snapping of lines to baselines. It works with normal flow, positioning and floats and
with pagination, as long as the grid is inside the pagination context and not outside.

Reviewed by Simon Fraser.

Added a bunch of new tests in fast/line-grid.

* WebCore.xcodeproj/project.pbxproj:
* rendering/InlineFlowBox.h:
(WebCore::InlineFlowBox::setHasTextChildren):
* rendering/LayoutState.cpp:
(WebCore::LayoutState::LayoutState):
(WebCore::LayoutState::propagateLineGridInfo):
(WebCore::LayoutState::establishLineGrid):
* rendering/LayoutState.h:
(WebCore::LayoutState::LayoutState):
(WebCore::LayoutState::pageLogicalHeight):
(WebCore::LayoutState::currentLineGrid):
(WebCore::LayoutState::currentLineGridOffset):
(WebCore::LayoutState::layoutOffset):
(WebCore::LayoutState::needsBlockDirectionLocationSetBeforeLayout):
* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::layoutBlockChildren):
(WebCore::RenderBlock::layoutPositionedObjects):
(WebCore::RenderBlock::insertFloatingObject):
(WebCore::RenderBlock::positionNewFloats):
(WebCore::RenderBlock::pageLogicalTopForOffset):
(WebCore::RenderBlock::adjustLinePositionForPagination):
* rendering/RenderBlock.h:
(WebCore::RenderBlock::lineGridBox):
(WebCore::RenderBlock::setLineGridBox):
(WebCore::RenderBlock::RenderBlockRareData::RenderBlockRareData):
* rendering/RenderBlockLineLayout.cpp:
(WebCore::RenderBlock::layoutInlineChildren):
(WebCore::RenderBlock::layoutLineGridBox):
* rendering/RenderFlowThread.cpp:
(WebCore::RenderFlowThread::regionLogicalTopForLine):
* rendering/RenderFlowThread.h:
* rendering/RenderView.h:
(WebCore::RenderView::pushLayoutState):
* rendering/RootInlineBox.cpp:
(WebCore::RootInlineBox::alignBoxesInBlockDirection):
(WebCore::RootInlineBox::lineGridSnapAdjustment):
* rendering/RootInlineBox.h:

LayoutTests: https://bugs.webkit.org/show_bug.cgi?id=76197

Add tests for baseline line grid alignment.

Reviewed by Simon Fraser.

* fast/line-grid/line-grid-floating.html: Added.
* fast/line-grid/line-grid-inside-columns.html: Added.
* fast/line-grid/line-grid-into-floats.html: Added.
* fast/line-grid/line-grid-positioned.html: Added.
* platform/mac/fast/line-grid: Added.
* platform/mac/fast/line-grid/line-grid-floating-expected.png: Added.
* platform/mac/fast/line-grid/line-grid-floating-expected.txt: Added.
* platform/mac/fast/line-grid/line-grid-inside-columns-expected.png: Added.
* platform/mac/fast/line-grid/line-grid-inside-columns-expected.txt: Added.
* platform/mac/fast/line-grid/line-grid-into-floats-expected.png: Added.
* platform/mac/fast/line-grid/line-grid-into-floats-expected.txt: Added.
* platform/mac/fast/line-grid/line-grid-positioned-expected.png: Added.
* platform/mac/fast/line-grid/line-grid-positioned-expected.txt: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105176 268f45cc-cd09-0410-ab3c-d52691b4dbfc