Get rid of NULLs in xfa/

xfa/fwl/basewidget/fwl_pushbuttonimp.cpp

Index: xfa/fwl/basewidget/fwl_pushbuttonimp.cpp
diff --git a/xfa/fwl/basewidget/fwl_pushbuttonimp.cpp b/xfa/fwl/basewidget/fwl_pushbuttonimp.cpp
index 77c93f4537ac453e578d48efcf3aa7407c555f9d..6806a2161ade88414e27196344ddd432325145b0 100644
--- a/xfa/fwl/basewidget/fwl_pushbuttonimp.cpp
+++ b/xfa/fwl/basewidget/fwl_pushbuttonimp.cpp
@@ -67,9 +67,9 @@ FWL_Error CFWL_PushButtonImp::GetWidgetRect(CFX_RectF& rect,
                                             FX_BOOL bAutoSize) {
   if (bAutoSize) {
     rect.Set(0, 0, 0, 0);
-    if (m_pProperties->m_pThemeProvider == NULL) {
+    if (!m_pProperties->m_pThemeProvider)
       m_pProperties->m_pThemeProvider = GetAvailableTheme();
-    }
+
     CFX_WideString wsCaption;
     IFWL_PushButtonDP* pData =
         static_cast<IFWL_PushButtonDP*>(m_pProperties->m_pDataProvider);
@@ -122,7 +122,7 @@ FWL_Error CFWL_PushButtonImp::DrawWidget(CFX_Graphics* pGraphics,
     return FWL_Error::Indefinite;
   IFWL_PushButtonDP* pData =
       static_cast<IFWL_PushButtonDP*>(m_pProperties->m_pDataProvider);
-  CFX_DIBitmap* pPicture = NULL;
+  CFX_DIBitmap* pPicture = nullptr;
   IFWL_ThemeProvider* pTheme = m_pProperties->m_pThemeProvider;
   if (HasBorder()) {
     DrawBorder(pGraphics, CFWL_Part::Border, m_pProperties->m_pThemeProvider,