Get rid of NULLs in fpdfsdk/

Review-Url: https://codereview.chromium.org/2031653003
diff --git a/fpdfsdk/javascript/JS_GlobalData.cpp b/fpdfsdk/javascript/JS_GlobalData.cpp
index b34bf09..aaa25ff 100644
--- a/fpdfsdk/javascript/JS_GlobalData.cpp
+++ b/fpdfsdk/javascript/JS_GlobalData.cpp
@@ -280,7 +280,7 @@
 }
 
 void CJS_GlobalData::LoadGlobalPersistentVariables() {
-  uint8_t* pBuffer = NULL;
+  uint8_t* pBuffer = nullptr;
   int32_t nLength = 0;
 
   LoadFileBuffer(m_sFilePath.c_str(), pBuffer, nLength);