[CSS Shapes] Normalize margin box size

Source/core/layout/shapes/ShapeOutsideInfo.cpp

 /*
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
  *    disclaimer.
@@ skipping 58 matching lines @@
         if (isHorizontalWritingMode)
             newReferenceBoxLogicalSize.shrink(m_renderer.borderAndPaddingWidth(), m_renderer.borderAndPaddingHeight());
         else
             newReferenceBoxLogicalSize.shrink(m_renderer.borderAndPaddingHeight(), m_renderer.borderAndPaddingWidth());
         break;
     case BoxMissing:
         ASSERT_NOT_REACHED();
         break;
     }
 
+    newReferenceBoxLogicalSize.clampNegativeToZero();
+
     if (m_referenceBoxLogicalSize == newReferenceBoxLogicalSize)
         return;
     markShapeAsDirty();
     m_referenceBoxLogicalSize = newReferenceBoxLogicalSize;
 }
 
 static bool checkShapeImageOrigin(Document& document, const StyleImage& styleImage)
 {
     if (styleImage.isGeneratedImage())
         return true;
@@ skipping 191 matching lines @@
 }
 ShapeOutsideDeltas ShapeOutsideInfo::computeDeltasForContainingBlockLine(const LayoutBlockFlow& containingBlock, const FloatingObject& floatingObject, LayoutUnit lineTop, LayoutUnit lineHeight)
 {
     ASSERT(lineHeight >= 0);
 
     LayoutUnit borderBoxTop = containingBlock.logicalTopForFloat(&floatingObject) + containingBlock.marginBeforeForChild(m_renderer);
     LayoutUnit borderBoxLineTop = lineTop - borderBoxTop;
 
     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));
             if (segment.isValid) {
                 LayoutUnit logicalLeftMargin = containingBlock.style()->isLeftToRightDirection() ? containingBlock.marginStartForChild(m_renderer) : containingBlock.marginEndForChild(m_renderer);
                 LayoutUnit rawLeftMarginBoxDelta = segment.logicalLeft + logicalLeftOffset() + logicalLeftMargin;
                 LayoutUnit leftMarginBoxDelta = clampTo<LayoutUnit>(rawLeftMarginBoxDelta, LayoutUnit(), floatMarginBoxWidth);
 
                 LayoutUnit logicalRightMargin = containingBlock.style()->isLeftToRightDirection() ? containingBlock.marginEndForChild(m_renderer) : containingBlock.marginStartForChild(m_renderer);
                 LayoutUnit rawRightMarginBoxDelta = segment.logicalRight + logicalLeftOffset() - containingBlock.logicalWidthForChild(m_renderer) - logicalRightMargin;
@@ skipping 42 matching lines @@
 }
 
 FloatSize ShapeOutsideInfo::shapeToRendererSize(FloatSize size) const
 {
     if (!m_renderer.style()->isHorizontalWritingMode())
         return size.transposedSize();
     return size;
 }
 
 } // namespace blink