https://bugs.webkit.org/show_bug.cgi?id=119801

Reviewed by Andreas Kling.

From Blink r148833, r148878, r150403 by <jchaffraix@chromium.org>

Source/WebCore:

Both grid-{column|row}-end and negative positions were not
properly handled in our grid position resolution code. We were
using the same code to resolve all the grid positions without
considering the edges of the grid.

Also refactored the grid size estimation in
resolveGridPositionsFromStyle() so we can use it for the grid size
estimation. The code no longer requires the grid to be filled at
that moment as the specs changed to use the "explicit grid" which
is independent of grid items (only depends on style).

Test: fast/css-grid-layout/grid-item-negative-position-resolution.html

* rendering/RenderGrid.cpp:
(WebCore::RenderGrid::maximumIndexInDirection):
(WebCore::RenderGrid::resolveGridPositionsFromStyle):
(WebCore::adjustGridPositionForSide):
(WebCore::RenderGrid::resolveGridPositionFromStyle):
* rendering/RenderGrid.h:

LayoutTests:

Added a new test to check negative position resolution. Also added
several new test cases to check that we properly resolve grid
positions in the grid edges.

* fast/css-grid-layout/grid-item-negative-position-resolution-expected.txt: Added.
* fast/css-grid-layout/grid-item-negative-position-resolution.html: Added.
* fast/css-grid-layout/grid-item-spanning-resolution-expected.txt:
* fast/css-grid-layout/grid-item-spanning-resolution.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@154731 268f45cc-cd09-0410-ab3c-d52691b4dbfc