[LayoutReloaded] Introduce Display.Box

[LayoutReloaded] Introduce Display.Box
https://bugs.webkit.org/show_bug.cgi?id=183700

Reviewed by Antti Koivisto.

Display.Box objects will end up in the display(box) tree. Currently
they are just hanging off of the Layout.Box objects.

* LayoutReloaded/DisplayTree/Box.js: Added.
(Display.Box):
(Display.Box.prototype.rect):
(Display.Box.prototype.top):
(Display.Box.prototype.left):
(Display.Box.prototype.bottom):
(Display.Box.prototype.right):
(Display.Box.prototype.topLeft):
(Display.Box.prototype.bottomRight):
(Display.Box.prototype.setTopLeft):
(Display.Box.prototype.setSize):
(Display.Box.prototype.setWidth):
(Display.Box.prototype.setHeight):
(Display.Box.prototype.borderBox):
(Display.Box.prototype.paddingBox):
(Display.Box.prototype.contentBox):
* LayoutReloaded/FormattingContext/BlockFormatting/BlockFormattingContext.js:
(BlockFormattingContext):
(BlockFormattingContext.prototype.layout):
(BlockFormattingContext.prototype._toAbsolutePosition):
(BlockFormattingContext.prototype._needsLayout):
(BlockFormattingContext.prototype._addToLayoutQueue):
(BlockFormattingContext.prototype._nextInLayoutQueue):
(BlockFormattingContext.prototype._removeFromLayoutQueue):
(BlockFormattingContext.prototype._createDisplayBox):
(BlockFormattingContext.prototype._toDisplayBox):
(BlockFormattingContext.prototype._toLayoutBox):
* LayoutReloaded/Layout.js:
(layout):
* LayoutReloaded/LayoutReloaded.xcworkspace/contents.xcworkspacedata:
* LayoutReloaded/LayoutTree/Box.js:
(Layout.Box):
(Layout.Box.prototype.setDisplayBox):
(Layout.Box.prototype.displayBox):
(Layout.Box.prototype.rect):
(Layout.Box.prototype.setTopLeft):
(Layout.Box.prototype.setSize):
(Layout.Box.prototype.setWidth):
(Layout.Box.prototype.setHeight):
(Layout.Box.prototype.borderBox):
(Layout.Box.prototype.paddingBox):
(Layout.Box.prototype.contentBox):
* LayoutReloaded/test/index.html:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@229671 268f45cc-cd09-0410-ab3c-d52691b4dbfc