Bug 269472 Crash opening about:plugins[@ JS_GetPrivate][@ PL_strcmp]

Caused by the careless fix for:
Bug 265936 Memory leak in nsPluginHostImpl::ScanPluginsDirectory()
I'm backing it out. People can play with it in their tree.

modules/plugin/base/src/nsPluginHostImpl.cpp

@@ -4858,8 +4858,6 @@ nsresult nsPluginHostImpl::ScanPluginsDirectory(nsIFile * pluginsDir,
     // if we are not creating the list, just continue the loop
     // no need to proceed if changes are detected
     if (!aCreatePluginList) {
-      delete pluginTag;
-
       if (*aPluginsChanged)
         return NS_OK;
       else