Ruby: Update beforeChild when redirecting renderer insertion to a child.

Source/core/rendering/RenderRubyRun.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 113 matching lines @@
             // In this case we need insert a new run before the current one and split the base.
             RenderObject* ruby = parent();
             RenderRubyRun* newRun = staticCreateRubyRun(ruby);
             ruby->addChild(newRun, this);
             newRun->addChild(child);
             rubyBaseSafe()->moveChildren(newRun->rubyBaseSafe(), beforeChild);
         }
     } else {
         // child is not a text -> insert it into the base
         // (append it instead if beforeChild is the ruby text)
+        RenderRubyBase* base = rubyBaseSafe();
+        if (beforeChild == base)
+            beforeChild = base->firstChild();
         if (beforeChild && beforeChild->isRubyText())
             beforeChild = 0;
-        rubyBaseSafe()->addChild(child, beforeChild);
+        ASSERT(!beforeChild || beforeChild->isDescendantOf(base));
+        base->addChild(child, beforeChild);
     }
 }
 
 void RenderRubyRun::removeChild(RenderObject* child)
 {
     // If the child is a ruby text, then merge the ruby base with the base of
     // the right sibling run, if possible.
     if (!beingDestroyed() && !documentBeingDestroyed() && child->isRubyText()) {
         RenderRubyBase* base = rubyBase();
         RenderObject* rightNeighbour = nextSibling();
@@ skipping 145 matching lines @@
     // We can overhang the ruby by no more than half the width of the neighboring text
     // and no more than half the font size.
     int halfWidthOfFontSize = rubyText->style(firstLine)->fontSize() / 2;
     if (startOverhang)
         startOverhang = std::min<int>(startOverhang, std::min<int>(toRenderText(startRenderer)->minLogicalWidth(), halfWidthOfFontSize));
     if (endOverhang)
         endOverhang = std::min<int>(endOverhang, std::min<int>(toRenderText(endRenderer)->minLogicalWidth(), halfWidthOfFontSize));
 }
 
 } // namespace blink