Use ContainerNode::hasChildren() instead of firstChild() in conditionals

Source/core/editing/ApplyStyleCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2008, 2009 Apple 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:
  * 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 1430 matching lines @@
     HTMLElement* styleContainer = 0;
     for (Node* container = startNode.get(); container && startNode == endNode; container = container->firstChild()) {
         if (isHTMLFontElement(*container))
             fontContainer = toHTMLFontElement(container);
         bool styleContainerIsNotSpan = !isHTMLSpanElement(styleContainer);
         if (container->isHTMLElement()) {
             HTMLElement* containerElement = toHTMLElement(container);
             if (isHTMLSpanElement(*containerElement) || (styleContainerIsNotSpan && containerElement->hasChildren()))
                 styleContainer = toHTMLElement(container);
         }
-        if (!container->firstChild())
+        if (!container->hasChildren())
             break;
         startNode = container->firstChild();
         endNode = container->lastChild();
     }
 
     // Font tags need to go outside of CSS so that CSS font sizes override leagcy font sizes.
     if (styleChange.applyFontColor() || styleChange.applyFontFace() || styleChange.applyFontSize()) {
         if (fontContainer) {
             if (styleChange.applyFontColor())
                 setNodeAttribute(fontContainer, colorAttr, AtomicString(styleChange.fontColor()));
@@ skipping 109 matching lines @@
 void ApplyStyleCommand::trace(Visitor* visitor)
 {
     visitor->trace(m_style);
     visitor->trace(m_start);
     visitor->trace(m_end);
     visitor->trace(m_styledInlineElement);
     CompositeEditCommand::trace(visitor);
 }
 
 }