Get rid of NULLs in fpdfsdk/

fpdfsdk/formfiller/cffl_combobox.cpp

Index: fpdfsdk/formfiller/cffl_combobox.cpp
diff --git a/fpdfsdk/formfiller/cffl_combobox.cpp b/fpdfsdk/formfiller/cffl_combobox.cpp
index 8b2da626b2a711e54c025cd03d6a44b08253360f..d489a243d9a488e6156812db1aa68f3f00b4672a 100644
--- a/fpdfsdk/formfiller/cffl_combobox.cpp
+++ b/fpdfsdk/formfiller/cffl_combobox.cpp
@@ -14,7 +14,7 @@
 #include "fpdfsdk/pdfwindow/PWL_ComboBox.h"
 
 CFFL_ComboBox::CFFL_ComboBox(CPDFDoc_Environment* pApp, CPDFSDK_Annot* pAnnot)
-    : CFFL_FormFiller(pApp, pAnnot), m_pFontMap(NULL) {
+    : CFFL_FormFiller(pApp, pAnnot), m_pFontMap(nullptr) {
   m_State.nIndex = 0;
   m_State.nStart = 0;
   m_State.nEnd = 0;
@@ -227,7 +227,7 @@ CPWL_Wnd* CFFL_ComboBox::ResetPDFWindow(CPDFSDK_PageView* pPageView,
 
   DestroyPDFWindow(pPageView);
 
-  CPWL_Wnd* pRet = NULL;
+  CPWL_Wnd* pRet = nullptr;
 
   if (bRestoreValue) {
     RestoreState(pPageView);