Avoid using NULL comparison to check if element is in the map.

native_client/src/trusted/plugin/plugin.cc

Index: native_client/src/trusted/plugin/plugin.cc
===================================================================
--- native_client/src/trusted/plugin/plugin.cc	(revision 147940)
+++ native_client/src/trusted/plugin/plugin.cc	(working copy)
@@ -493,17 +493,18 @@
 bool Plugin::HasProperty(const nacl::string& prop_name) {
   PLUGIN_PRINTF(("Plugin::HasProperty (prop_name=%s)\n",
                  prop_name.c_str()));
-  return property_getters_[prop_name] != NULL;
+  return property_getters_.find(prop_name) != property_getters_.end();
 }
 
 bool Plugin::GetProperty(const nacl::string& prop_name,
                          NaClSrpcArg* prop_value) {
   PLUGIN_PRINTF(("Plugin::GetProperty (prop_name=%s)\n", prop_name.c_str()));
 
-  PropertyGetter getter = property_getters_[prop_name];
-  if (NULL == getter) {
+  if (property_getters_.find(prop_name) == property_getters_.end()) {
     return false;
   }
+
+  PropertyGetter getter = property_getters_[prop_name];
   (this->*getter)(prop_value);
   return true;
 }