[CSS Shapes] Normalize margin box size

Source/core/layout/shapes/ShapeOutsideInfo.cpp

Index: Source/core/layout/shapes/ShapeOutsideInfo.cpp
diff --git a/Source/core/layout/shapes/ShapeOutsideInfo.cpp b/Source/core/layout/shapes/ShapeOutsideInfo.cpp
index 8e2f81d369b722b9b5020478835df591fe79ed71..eea6568ab106225e2a466d08aa62dfbf693359a7 100644
--- a/Source/core/layout/shapes/ShapeOutsideInfo.cpp
+++ b/Source/core/layout/shapes/ShapeOutsideInfo.cpp
@@ -76,6 +76,8 @@ void ShapeOutsideInfo::setReferenceBoxLogicalSize(LayoutSize newReferenceBoxLogi
         break;
     }
 
+    newReferenceBoxLogicalSize.clampNegativeToZero();
+
     if (m_referenceBoxLogicalSize == newReferenceBoxLogicalSize)
         return;
     markShapeAsDirty();
@@ -287,7 +289,7 @@ ShapeOutsideDeltas ShapeOutsideInfo::computeDeltasForContainingBlockLine(const L
 
     if (isShapeDirty() || !m_shapeOutsideDeltas.isForLine(borderBoxLineTop, lineHeight)) {
         LayoutUnit referenceBoxLineTop = borderBoxLineTop - logicalTopOffset();
-        LayoutUnit floatMarginBoxWidth = containingBlock.logicalWidthForFloat(&floatingObject);
+        LayoutUnit floatMarginBoxWidth = std::max(containingBlock.logicalWidthForFloat(&floatingObject), LayoutUnit());
 
         if (computedShape().lineOverlapsShapeMarginBounds(referenceBoxLineTop, lineHeight)) {
             LineSegment segment = computedShape().getExcludedInterval((borderBoxLineTop - logicalTopOffset()), std::min(lineHeight, shapeLogicalBottom() - borderBoxLineTop));