Get rid of most instance of 'foo == NULL'

fpdfsdk/src/javascript/Document.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "Document.h"
 
 #include "Field.h"
 #include "Icon.h"
@@ skipping 1241 matching lines @@
 
 bool Document::IsEnclosedInRect(CFX_FloatRect rect, CFX_FloatRect LinkRect) {
   return (rect.left <= LinkRect.left && rect.top <= LinkRect.top &&
           rect.right >= LinkRect.right && rect.bottom >= LinkRect.bottom);
 }
 
 void IconTree::InsertIconElement(IconElement* pNewIcon) {
   if (!pNewIcon)
     return;
 
-  if (m_pHead == NULL && m_pEnd == NULL) {
-    m_pHead = m_pEnd = pNewIcon;
-    m_iLength++;
-  } else {
+  if (m_pHead || m_pEnd) {
     m_pEnd->NextIcon = pNewIcon;
     m_pEnd = pNewIcon;
-    m_iLength++;
+  } else {
+    m_pHead = pNewIcon;
+    m_pEnd = pNewIcon;
   }
+  m_iLength++;
 }
 
 void IconTree::DeleteIconTree() {
   if (!m_pHead || !m_pEnd)
     return;
 
   IconElement* pTemp = NULL;
   while (m_pEnd != m_pHead) {
     pTemp = m_pHead;
     m_pHead = m_pHead->NextIcon;
@@ skipping 493 matching lines @@
   CFX_DWordArray DelArray;
 
   for (int j = DelArray.GetSize() - 1; j >= 0; j--) {
     m_DelayData.RemoveAt(DelArray[j]);
   }
 }
 
 CJS_Document* Document::GetCJSDoc() const {
   return static_cast<CJS_Document*>(m_pJSObject);
 }