--- a/layout/generic/nsFloatManager.cpp
+++ b/layout/generic/nsFloatManager.cpp
@@ -524,52 +524,52 @@ nsFloatManager::ClearContinues(StyleClea
           (aBreakType == StyleClear::Both ||
            aBreakType == StyleClear::Left)) ||
          ((mPushedRightFloatPastBreak || mSplitRightFloatAcrossBreak) &&
           (aBreakType == StyleClear::Both ||
            aBreakType == StyleClear::Right));
 }
 
 /////////////////////////////////////////////////////////////////////////////
-// BoxShapeInfo
+// RoundedBoxShapeInfo
 
 nscoord
-nsFloatManager::BoxShapeInfo::LineLeft(WritingMode aWM,
-                                       const nscoord aBStart,
-                                       const nscoord aBEnd) const
+nsFloatManager::RoundedBoxShapeInfo::LineLeft(WritingMode aWM,
+                                              const nscoord aBStart,
+                                              const nscoord aBEnd) const
 {
   if (!mRadii) {
-    return mShapeBoxRect.x;
+    return mRect.x;
   }
 
   nscoord lineLeftDiff =
     ComputeEllipseLineInterceptDiff(
-      mShapeBoxRect.y, mShapeBoxRect.YMost(),
+      mRect.y, mRect.YMost(),
       mRadii[eCornerTopLeftX], mRadii[eCornerTopLeftY],
       mRadii[eCornerBottomLeftX], mRadii[eCornerBottomLeftY],
       aBStart, aBEnd);
-  return mShapeBoxRect.x + lineLeftDiff;
+  return mRect.x + lineLeftDiff;
 }
 
 nscoord
-nsFloatManager::BoxShapeInfo::LineRight(WritingMode aWM,
-                                        const nscoord aBStart,
-                                        const nscoord aBEnd) const
+nsFloatManager::RoundedBoxShapeInfo::LineRight(WritingMode aWM,
+                                               const nscoord aBStart,
+                                               const nscoord aBEnd) const
 {
   if (!mRadii) {
-    return mShapeBoxRect.XMost();
+    return mRect.XMost();
   }
 
   nscoord lineRightDiff =
     ComputeEllipseLineInterceptDiff(
-      mShapeBoxRect.y, mShapeBoxRect.YMost(),
+      mRect.y, mRect.YMost(),
       mRadii[eCornerTopRightX], mRadii[eCornerTopRightY],
       mRadii[eCornerBottomRightX], mRadii[eCornerBottomRightY],
       aBStart, aBEnd);
-  return mShapeBoxRect.XMost() - lineRightDiff;
+  return mRect.XMost() - lineRightDiff;
 }
 
 /////////////////////////////////////////////////////////////////////////////
 // EllipseShapeInfo
 nscoord
 nsFloatManager::EllipseShapeInfo::LineLeft(WritingMode aWM,
                                            const nscoord aBStart,
                                            const nscoord aBEnd) const
@@ -801,22 +801,23 @@ nsFloatManager::ShapeInfo::CreateShapeBo
   const nsSize& aContainerSize)
 {
   nsRect logicalShapeBoxRect
     = ConvertToFloatLogical(aShapeBoxRect, aWM, aContainerSize);
 
   nscoord physicalRadii[8];
   bool hasRadii = aFrame->GetShapeBoxBorderRadii(physicalRadii);
   if (!hasRadii) {
-    return MakeUnique<BoxShapeInfo>(logicalShapeBoxRect,
-                                    UniquePtr<nscoord[]>());
+    return MakeUnique<RoundedBoxShapeInfo>(logicalShapeBoxRect,
+                                           UniquePtr<nscoord[]>());
   }
 
-  return MakeUnique<BoxShapeInfo>(logicalShapeBoxRect,
-                                  ConvertToFloatLogical(physicalRadii, aWM));
+  return MakeUnique<RoundedBoxShapeInfo>(logicalShapeBoxRect,
+                                         ConvertToFloatLogical(physicalRadii,
+                                                               aWM));
 }
 
 /* static */ UniquePtr<nsFloatManager::ShapeInfo>
 nsFloatManager::ShapeInfo::CreateCircleOrEllipse(
   StyleBasicShape* const aBasicShape,
   const LogicalRect& aShapeBoxRect,
   WritingMode aWM,
   const nsSize& aContainerSize)

--- a/layout/generic/nsFloatManager.h
+++ b/layout/generic/nsFloatManager.h
@@ -416,45 +416,44 @@ private:
     // Convert the half corner radii (nscoord[8]) to the special logical
     // coordinate space used in float manager.
     static mozilla::UniquePtr<nscoord[]> ConvertToFloatLogical(
       const nscoord aRadii[8],
       mozilla::WritingMode aWM);
   };
 
   // Implements shape-outside: <shape-box>.
-  class BoxShapeInfo final : public ShapeInfo
+  class RoundedBoxShapeInfo final : public ShapeInfo
   {
   public:
-    BoxShapeInfo(const nsRect& aShapeBoxRect,
-                 mozilla::UniquePtr<nscoord[]> aRadii)
-      : mShapeBoxRect(aShapeBoxRect)
+    RoundedBoxShapeInfo(const nsRect& aRect,
+                        mozilla::UniquePtr<nscoord[]> aRadii)
+      : mRect(aRect)
       , mRadii(Move(aRadii))
     {}
 
     nscoord LineLeft(mozilla::WritingMode aWM,
                      const nscoord aBStart,
                      const nscoord aBEnd) const override;
     nscoord LineRight(mozilla::WritingMode aWM,
                       const nscoord aBStart,
                       const nscoord aBEnd) const override;
-    nscoord BStart() const override { return mShapeBoxRect.y; }
-    nscoord BEnd() const override { return mShapeBoxRect.YMost(); }
-    bool IsEmpty() const override { return mShapeBoxRect.IsEmpty(); };
+    nscoord BStart() const override { return mRect.y; }
+    nscoord BEnd() const override { return mRect.YMost(); }
+    bool IsEmpty() const override { return mRect.IsEmpty(); };
 
     void Translate(nscoord aLineLeft, nscoord aBlockStart) override
     {
-      mShapeBoxRect.MoveBy(aLineLeft, aBlockStart);
+      mRect.MoveBy(aLineLeft, aBlockStart);
     }
 
   private:
-    // This is the reference box of css shape-outside if specified, which
-    // implements the <shape-box> value in the CSS Shapes Module Level 1.
-    // The coordinate space is the same as FloatInfo::mRect.
-    nsRect mShapeBoxRect;
+    // The rect of the rounded box shape in the float manager's coordinate
+    // space.
+    nsRect mRect;
     // The half corner radii of the reference box. It's an nscoord[8] array
     // in the float manager's coordinate space. If there are no radii, it's
     // nullptr.
     mozilla::UniquePtr<nscoord[]> mRadii;
   };
 
   // Implements shape-outside: circle() and shape-outside: ellipse().
   class EllipseShapeInfo : public ShapeInfo