Issue #1230 - Part 1: Fix Back-computing percentages for intrinsic sizing in Layout CSS-Grid

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.)

3 files changed, 4 insertions, 4 deletions

diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 2049f70e8..07db6d3dd 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -1499,7 +1499,7 @@ CSS_PROP_COLUMN(
     CSS_PROPERTY_PARSE_VALUE |
         CSS_PROPERTY_VALUE_NONNEGATIVE,
     "",
-    VARIANT_HL | VARIANT_NORMAL | VARIANT_CALC,
+    VARIANT_HLP | VARIANT_NORMAL | VARIANT_CALC,
     nullptr,
     offsetof(nsStyleColumn, mColumnGap),
     eStyleAnimType_Coord)
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index c8182b8f1..b257c6bb5 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -3495,7 +3495,7 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleColumn
 
   uint32_t     mColumnCount; // [reset] see nsStyleConsts.h
   nsStyleCoord mColumnWidth; // [reset] coord, auto
-  nsStyleCoord mColumnGap;   // [reset] coord, normal
+  nsStyleCoord mColumnGap;   // [reset] <length-percentage> | normal
 
   mozilla::StyleComplexColor mColumnRuleColor; // [reset]
   uint8_t      mColumnRuleStyle;  // [reset]
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index 272931c15..c75f7b498 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -1438,7 +1438,7 @@ var gCSSProperties = {
     inherited: false,
     type: CSS_TYPE_LONGHAND,
     initial_values: [ "normal", "1em", "calc(-2em + 3em)" ],
-    other_values: [ "2px", "4em",
+    other_values: [ "2px", "1em", "4em", "3%", "calc(3%)", "calc(1em - 3%)",
       "calc(2px)",
       "calc(-2px)",
       "calc(0px)",
@@ -1448,7 +1448,7 @@ var gCSSProperties = {
       "calc(25px*3)",
       "calc(3*25px + 5em)",
     ],
-    invalid_values: [ "3%", "-1px", "4" ]
+    invalid_values: [ "-3%", "-1px", "4" ]
   },
   "-moz-column-gap": {
     domProp: "MozColumnGap",