Bug 1740580 - Align shrink-wrap behavior of semi-replaced elements with the spec. r=dholbert,layout-reviewers

The removed reftsts test basically the opposite, and are sufficiently
covered by the WPTs that we start passing, so just remove them.

Differential Revision: https://phabricator.services.mozilla.com/D204797

layout/generic/ReflowInput.h

@@ -367,6 +367,16 @@ struct ReflowInput : public SizeComputationInput {
 
   mozilla::LogicalSize AvailableSize() const { return mAvailableSize; }
   mozilla::LogicalSize ComputedSize() const { return mComputedSize; }
+
+  template <typename F>
+  mozilla::LogicalSize ComputedSizeWithBSizeFallback(F&& aFallback) const {
+    auto size = mComputedSize;
+    if (size.BSize(mWritingMode) == NS_UNCONSTRAINEDSIZE) {
+      size.BSize(mWritingMode) = ApplyMinMaxBSize(aFallback());
+    }
+    return size;
+  }
+
   mozilla::LogicalSize ComputedMinSize() const { return mComputedMinSize; }
   mozilla::LogicalSize ComputedMaxSize() const { return mComputedMaxSize; }