Bug 1584018 - Make flex and grid code indicate that its block resizes can affect basis for percentages. r=dholbert,mats

Differential Revision: https://phabricator.services.mozilla.com/D50511

--HG--
extra : moz-landing-system : lando

layout/generic/nsFlexContainerFrame.cpp

@@ -1865,6 +1865,8 @@ nscoord nsFlexContainerFrame::MeasureFlexItemContentBSize(
 
   if (aForceBResizeForMeasuringReflow) {
     childRIForMeasuringBSize.SetBResize(true);
+    // Not 100% sure this is needed, but be conservative for now:
+    childRIForMeasuringBSize.mFlags.mIsBResizeForPercentages = true;
   }
 
   const CachedMeasuringReflowResult& reflowResult =
@@ -4232,6 +4234,8 @@ void nsFlexContainerFrame::SizeItemInCrossAxis(
     // (Note: we know that the cross axis is the item's *block* axis -- if it
     // weren't, then we would've taken the early-return above.)
     aChildReflowInput.SetBResize(true);
+    // Not 100% sure this is needed, but be conservative for now:
+    aChildReflowInput.mFlags.mIsBResizeForPercentages = true;
   }
 
   // Potentially reflow the item, and get the sizing info.
@@ -5248,6 +5252,7 @@ void nsFlexContainerFrame::ReflowFlexItem(
     }
     if (didOverrideComputedBSize) {
       childReflowInput.SetBResize(true);
+      childReflowInput.mFlags.mIsBResizeForPercentages = true;
     }
   }
   // NOTE: Be very careful about doing anything else with childReflowInput

layout/generic/nsGridContainerFrame.cpp

@@ -4634,6 +4634,8 @@ static nscoord MeasuringReflow(nsIFrame* aChild,
   // child does some of the things that are affected by
   // ReflowInput::COMPUTE_SIZE_USE_AUTO_BSIZE.
   childRI.SetBResize(true);
+  // Not 100% sure this is needed, but be conservative for now:
+  childRI.mFlags.mIsBResizeForPercentages = true;
 
   ReflowOutput childSize(childRI);
   nsReflowStatus childStatus;
@@ -6379,6 +6381,7 @@ void nsGridContainerFrame::ReflowInFlowChild(
   // does some of the things that are affected by
   // ReflowInput::COMPUTE_SIZE_USE_AUTO_BSIZE.
   childRI.SetBResize(true);
+  childRI.mFlags.mIsBResizeForPercentages = true;
 
   // A table-wrapper needs to propagate the CB size we give it to its
   // inner table frame later.  @see nsTableWrapperFrame::InitChildReflowInput.

testing/web-platform/meta/css/css-flexbox/flex-child-percent-basis-resize-1.html.ini

@@ -1,2 +0,0 @@
-[flex-child-percent-basis-resize-1.html]
-  expected: FAIL

testing/web-platform/meta/css/css-grid/grid-child-percent-basis-resize-1.html.ini

@@ -1,2 +0,0 @@
-[grid-child-percent-basis-resize-1.html]
-  expected: FAIL