[LFC] Make BlockFormattingContext::Geometry a subclass of FormattingContext::Geometry

[LFC] Make BlockFormattingContext::Geometry a subclass of FormattingContext::Geometry
https://bugs.webkit.org/show_bug.cgi?id=189294

Reviewed by Antti Koivisto.

This simplifies some of the call sites.

* layout/blockformatting/BlockFormattingContext.cpp:
(WebCore::Layout::BlockFormattingContext::computeWidthAndMargin const):
(WebCore::Layout::BlockFormattingContext::computeHeightAndMargin const):
* layout/blockformatting/BlockFormattingContext.h:
* layout/blockformatting/BlockFormattingContextGeometry.cpp:
(WebCore::Layout::BlockFormattingContext::Geometry::inFlowNonReplacedHeightAndMargin):
(WebCore::Layout::BlockFormattingContext::Geometry::inFlowNonReplacedWidthAndMargin):
(WebCore::Layout::BlockFormattingContext::Geometry::inFlowReplacedWidthAndMargin):
(WebCore::Layout::BlockFormattingContext::Geometry::inFlowPositionedPosition):
(WebCore::Layout::BlockFormattingContext::Geometry::inFlowHeightAndMargin):
(WebCore::Layout::BlockFormattingContext::Geometry::instrinsicWidthConstraints):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@235667 268f45cc-cd09-0410-ab3c-d52691b4dbfc