Merge 133221 - REGRESSION (r128837): mathml/presentation/subsup.xhtml became flaky

Source/WebCore/rendering/mathml/RenderMathMLSubSup.cpp

 /*
  * Copyright (C) 2010 Alex Milowski (alex@milowski.com). 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 43 matching lines @@
 {
     RenderObject* baseWrapper = firstChild();
     if (!baseWrapper)
         return 0;
     RenderObject* base = baseWrapper->firstChild();
     if (!base || !base->isBoxModelObject())
         return 0;
     return toRenderBoxModelObject(base);
 }
 
-void RenderMathMLSubSup::fixScriptsStyle()
+void RenderMathMLSubSup::fixAnonymousStyles()
 {
+    // Set the base wrapper's style so that baseHeight in layout() will be an unstretched height.
+    ASSERT(firstChild() && firstChild()->style()->refCount() == 1);
+    firstChild()->style()->setAlignSelf(AlignFlexStart);
+    
     ASSERT(m_scripts && m_scripts->style()->refCount() == 1);
     RenderStyle* scriptsStyle = m_scripts->style();
     scriptsStyle->setFlexDirection(FlowColumn);
     scriptsStyle->setJustifyContent(m_kind == Sub ? JustifyFlexEnd : m_kind == Super ? JustifyFlexStart : JustifySpaceBetween);
     // Set this wrapper's font-size for its line-height & baseline position, for its children.
     scriptsStyle->setFontSize(static_cast<int>(0.75 * style()->fontSize()));
 }
 
 // FIXME: Handle arbitrary addChild/removeChild correctly throughout MathML.
 void RenderMathMLSubSup::addChild(RenderObject* child, RenderObject* beforeChild)
 {
     if (isEmpty()) {
         RenderMathMLBlock* baseWrapper = createAnonymousMathMLBlock();
         RenderMathMLBlock::addChild(baseWrapper);
         
         m_scripts = createAnonymousMathMLBlock();
         RenderMathMLBlock::addChild(m_scripts);
-        fixScriptsStyle();
+        
+        fixAnonymousStyles();
     }
     
     if (firstChild()->isEmpty())
         firstChild()->addChild(child);
     else
         m_scripts->addChild(child, beforeChild && beforeChild->parent() == m_scripts ? beforeChild : 0);
 }
 
 void RenderMathMLSubSup::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
 {
     RenderMathMLBlock::styleDidChange(diff, oldStyle);
     
-    if (m_scripts)
-        fixScriptsStyle();
+    if (!isEmpty())
+        fixAnonymousStyles();
 }
 
 RenderMathMLOperator* RenderMathMLSubSup::unembellishedOperator()
 {
     RenderBoxModelObject* base = this->base();
     if (!base || !base->isRenderMathMLBlock())
         return 0;
     return toRenderMathMLBlock(base)->unembellishedOperator();
 }
 
@@ skipping 44 matching lines @@
     
     setChildNeedsLayout(true, MarkOnlyThis);
     baseWrapper->setNeedsLayout(true, MarkOnlyThis);
     
     RenderMathMLBlock::layout();
 }
 
 }    
 
 #endif // ENABLE(MATHML)