Augment the properties exposed in bug 1241932 to include information on implicit and explicit grid areas.

Adds areas property to the grid objects returned by <element>.getGridFragments(). https://treeherder.mozilla.org/#/jobs?repo=try&revision=79379f4496c8

Quick update to support Gabe's prototype. Explicit GridAreas get bounding lines, but implicit GridAreas do not (yet).

Comment on attachment 8782147 [details] [diff] [review] gridAreas3.patch Current patch to get the bounding star/end row and column for css grid area has been working great!

Adds grid areas, add comments to the Grid.webidl explaining which numbers are 0-indexed and which are 1-indexed. Explicit grid areas get correct boundary lines; implicit grid areas get 0 for all boundary lines until Bug 1297189 resolves that. I'd like to land this to get the areas and the implicit/explicit state stuff to the dev tools team while working on the implicit boundary lines. https://treeherder.mozilla.org/#/jobs?repo=try&revision=072ad0d350fe

Comment on attachment 8783717 [details] [diff] [review] gridAreas4.patch r=mats on the layout changes. You should ask a DOM peer to review the rest.

Comment on attachment 8783717 [details] [diff] [review] gridAreas4.patch Requesting webidl review from bz as a DOM peer.

Comment on attachment 8783717 [details] [diff] [review] gridAreas4.patch This is going to return the implicit areas in some random order, right? Is that OK? Is there a reason for the separate SetAreaValues function instead of just passing that stuff to the constructor? Can any of those values change on a GridArea object? If not, it would be good to make them const on GridArea and pass them to the constructor. >+ (i > aTrackInfo->mNumLeadingImplicitTracks + >+ aTrackInfo->mNumExplicitTracks) ? Should this be > or >=? That is, if mNumExplicitTracks and mNumLeadingImplicitTracks are both 0, what should happen for i == 0? Should it be explicit or implicit? It's not clear to me why it should be explicit in that situation; the comment seems to say it should, but not _why_... >+ [Cached, Pure] >+ readonly attribute sequence<GridArea> areas; It's actually [Constant], not just [Pure], right? >+ readonly attribute sequence<DOMString> names; And this one too? Also, please put the extended attributes (the stuff in []) right before this line, not way off before the comment. r=me with those fixed.

Per review from bz: Consolidated GridArea setter into constructor, improved comments, and updated GridLine type. https://treeherder.mozilla.org/#/jobs?repo=try&revision=b263a9513cf7

https://hg.mozilla.org/integration/fx-team/rev/c98b8c992c2f3dfc4789deab913ca942ae61f304 Bug 1289200 - Adds GridAreas to grid css dev tools API. r=bz, mats