List of relevant patches applied:
1398537 part 2 - [css-multicol] Implement percentages for 'column-gap' (Gecko part).
1434478 part 1 - [css-grid] Stop back-computing percentage grid gaps when the percentage basis is indefinite. Treat them as zero sized instead.
1434478 part 2 - Stop back-computing percentage padding/margin when the percentage basis is indefinite. Treat them as zero sized instead.
1434478 part 3 - Remove IntrinsicISizeOffsetData::hPctPadding/hPctMargin members since they are now unused.
1434478 part 4 - Factor out constants like NS_UNCONSTRAINEDSIZE so they can be used in headers without needing nsIFrame.h (idempotent patch).
1434478 part 5 - Create nsLayoutUtils::ResolveToLength for resolving CSS <length-percentage> (idempotent patch).
1434478 part 6 - Propagate a percentage basis to nsIFrame::IntrinsicISizeOffsets for resolving padding/margin.
This is needed only for CSS Grid since in other cases we're only using IntrinsicISizeOffsets in the inline-axis and the percentage basis is always indefinite for *intrinsic sizing*. When calculating the intrinsic size of grid items in the grid container's block axis however, we do have a definite size for the grid area in the inline-axis and it should be used per: https://drafts.csswg.org/css-grid/#algo-overview "2. Next, the track sizing algorithm resolves the sizes of the grid rows, using the grid column sizes calculated in the previous step." (Percentage padding/margin for grid items is always resolved against the grid area's inline-size nowadays.)
List of relevant patches applied:
1425599 part 15 - [css-grid] Test reference fixes + more tests.
1373678 Part 3: Add line number checks to test_grid_implicit.html.
1416350 - Part 3: Add test to verify line numbers of grids with leading implicit tracks.
1416350 - Part 4: Add a reftest of repeat:auto-fit grids with leading implicit tracks.
1417711 - [css-grid] An abs.pos. grid container child that only covers removed 'auto-fit' tracks should not span to the end padding edge.
1416350 - Part 5: Correct the expected results for grids that have leading implicit tracks.
1418727 part 3 - [css-grid] Reftest updates.
List of relevant patches applied:
1425599 part 1 - [css-grid] Change the track sizing algorithm for spanning items so that it accumulates individual item contributions to the plan by max() rather than incrementing the planned size directly.
Also, fix a bug when copying back the planned limits after updating it for the first span group. It should only copy back track sizes that were actaully spanned by those items, other content-sized tracks' limits should remain at "infinity".
1425599 part 2 - [css-grid] Factor out the min-sizing parts of the track sizing for spanned items to a templated method (idempotent change).
1425599 part 3 - [css-grid] Factor out most of the max-sizing parts of the track sizing for spanned items to a templated method (idempotent change).
1425599 part 4 - [css-grid] Factor out the starting base/limit size to a templated method (idempotent change).
1425599 part 5 - [css-grid] Make CollectGrowable a templated method so that it works with either base/limit sizes (idempotent change).
1425599 part 6 - [css-grid] Make the size distribution methods templated with the intent of merging them in a later patch (idempotent change).
This patch also introduces an eInfinitelyGrowable bit to help get rid of the 'limits' temporary track sizes in the next patch.
1425599 part 7 - [css-grid] Remove the 'limits' copy of track sizes since they are no longer needed (idempotent change).
1425599 part 8 - [css-grid] Factor out the fit-content clamping function from DistributeToTrackLimits and pass it as a param instead (idempotent change).
1425599 part 9 - [css-grid] Merge DistributeToTrackLimits/Bases (idempotent change).
1425599 part 10 - [css-grid] Make MarkExcludedTracks a static method since it doesn't use 'this' (idempotent change).
1425599 part 11 - [css-grid] Hoist the marking of excluded tracks out from GrowSelectedTracksUnlimited to a separate method (idempotent change).
1425599 part 12 - [css-grid] Merge CopyPlanToBase/Limits into a templated method instead (idempotent change).
1425599 part 13 - [css-grid] Merge Grow[Base|Limits]ForSpanningItems into a templated method instead (idempotent change).
1425599 part 14 - [css-grid] Use iterators instead of an array + start/end index for the item data (idempotent change).
1425599 part 16 - [css-grid] Make SizeContributionForPhase a template.
1425599 - [css-grid] Follow-up bustage fix for stupid compiler warnings.
1378481 - Assign 'roundingError' in the default branch too, to avoid a maybe-uninitialized compiler warning.
1423292 - [css-grid] Add a couple of ItemState bits to Dump(), and make an ItemState assertion stricter (DEBUG-only changes).
1373678 Part 1: Reduce grid line numbers by count of leading implicit lines, minimum 0.
1416350 - Part 1: Correctly account for removed 'auto-fit' tracks also when there are leading implicit tracks.
1416350 - Part 2: Correct logic for Grid API line numbering with leading implicit tracks.
1418727 part 1 - [css-grid] Introduce StateBitsForRange() that collects the union of the state bits for a range of tracks (idempotent change).
1418727 part 2 - [css-grid] Require that an item spans at least one track with an 'auto' min sizing function for Automatic Minimum Size to apply.
This creates a number of stubs and leaves some surrounding code that may be irrelevant (eg. recorded time stamps, status variables).
Stub resolution/removal should be a follow-up to this.
