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

Source/core/html/HTMLTextFormControlElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 440 matching lines @@
         return nullptr;
 
     int start = m_cachedSelectionStart;
     int end = m_cachedSelectionEnd;
 
     ASSERT(start <= end);
     HTMLElement* innerText = innerEditorElement();
     if (!innerText)
         return nullptr;
 
-    if (!innerText->firstChild())
+    if (!innerText->hasChildren())
         return Range::create(document(), innerText, 0, innerText, 0);
 
     int offset = 0;
     Node* startNode = 0;
     Node* endNode = 0;
     for (Node* node = innerText->firstChild(); node; node = NodeTraversal::next(*node, innerText)) {
-        ASSERT(!node->firstChild());
+        ASSERT(!node->hasChildren());
         ASSERT(node->isTextNode() || isHTMLBRElement(*node));
         int length = node->isTextNode() ? lastOffsetInNode(node) : 1;
 
         if (offset <= start && start <= offset + length)
             setContainerAndOffsetForRange(node, start - offset, startNode, start);
 
         if (offset <= end && end <= offset + length) {
             setContainerAndOffsetForRange(node, end - offset, endNode, end);
             break;
         }
@@ skipping 432 matching lines @@
             Text* textNode = toText(node);
             size_t firstLineBreak = textNode->data().find('\n', isPivotNode ? pivotPosition.offsetInContainerNode() : 0);
             if (firstLineBreak != kNotFound)
                 return Position(textNode, firstLineBreak + 1);
         }
     }
     return endOfInnerText(textFormControl);
 }
 
 } // namespace Webcore