Refactoring: replace NULL by nullptr for pointers (3rd CL).

This CL mainly handles passing/returning NULL to/from a function.

BUG=angleproject:2001

Change-Id: I34802f792e710e3d7ff697cbe4701dc1bf5ab009
Reviewed-on: https://chromium-review.googlesource.com/485060
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/compiler/translator/VariableInfo.cpp b/src/compiler/translator/VariableInfo.cpp
index bc84aea..7673edc 100644
--- a/src/compiler/translator/VariableInfo.cpp
+++ b/src/compiler/translator/VariableInfo.cpp
@@ -60,7 +60,7 @@
             return &((*infoList)[ii]);
     }
 
-    return NULL;
+    return nullptr;
 }
 }