Refactoring: replace NULL by nullptr for pointers (2nd CL).

This CL mainly handles the pointer comparisons (== or !=).

BUG=angleproject:2001

Change-Id: I25ac3b61032e7ad91459a1c6541cadc87cf9b160
Reviewed-on: https://chromium-review.googlesource.com/483935
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/d3d/FramebufferD3D.cpp b/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
index 620b374..e176107 100644
--- a/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
+++ b/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
@@ -66,7 +66,8 @@
 
     if (mask & GL_DEPTH_BUFFER_BIT)
     {
-        if (state.getDepthStencilState().depthMask && framebufferObject->getDepthbuffer() != NULL)
+        if (state.getDepthStencilState().depthMask &&
+            framebufferObject->getDepthbuffer() != nullptr)
         {
             clearParams.clearDepth = true;
         }
@@ -74,7 +75,7 @@
 
     if (mask & GL_STENCIL_BUFFER_BIT)
     {
-        if (framebufferObject->getStencilbuffer() != NULL &&
+        if (framebufferObject->getStencilbuffer() != nullptr &&
             framebufferObject->getStencilbuffer()->getStencilSize() > 0)
         {
             clearParams.clearStencil = true;