Linux: Fix some NULL versus 0 issues to appease gcc-4.5.

webkit/glue/plugins/pepper_buffer.cc

Index: webkit/glue/plugins/pepper_buffer.cc
diff --git a/webkit/glue/plugins/pepper_buffer.cc b/webkit/glue/plugins/pepper_buffer.cc
index 1c0bdd87354e8646d0a09a6d920a307c18456322..7cd01950678f8fbd72c19ce51f16ca20f7df2070 100644
--- a/webkit/glue/plugins/pepper_buffer.cc
+++ b/webkit/glue/plugins/pepper_buffer.cc
@@ -22,11 +22,11 @@ namespace {
 PP_Resource Create(PP_Module module_id, int32_t size) {
   PluginModule* module = PluginModule::FromPPModule(module_id);
   if (!module)
-    return NULL;
+    return 0;
 
   scoped_refptr<Buffer> buffer(new Buffer(module));
   if (!buffer->Init(size))
-    return NULL;
+    return 0;
 
   return buffer->GetReference();
 }