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/tests/gl_tests/GLSLTest.cpp b/src/tests/gl_tests/GLSLTest.cpp
index f2c8b21..050651b 100644
--- a/src/tests/gl_tests/GLSLTest.cpp
+++ b/src/tests/gl_tests/GLSLTest.cpp
@@ -1699,7 +1699,7 @@
 
             std::string infoLog;
             infoLog.resize(infoLogLength);
-            glGetShaderInfoLog(shader, static_cast<GLsizei>(infoLog.size()), NULL, &infoLog[0]);
+            glGetShaderInfoLog(shader, static_cast<GLsizei>(infoLog.size()), nullptr, &infoLog[0]);
 
             if (infoLog.find("Loop index cannot be compared with non-constant expression") ==
                 std::string::npos)