Auto merge of #14671 - servo:style-no-plugins, r=mbrubeck

Remove the unused dependency of style to plugins.

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components/style/lib.rs

@@ -23,9 +23,7 @@
 //! [cssparser]: ../cssparser/index.html
 //! [selectors]: ../selectors/index.html
 
-#![cfg_attr(feature = "servo", feature(plugin))]
 #![cfg_attr(feature = "servo", feature(proc_macro))]
-#![cfg_attr(feature = "servo", plugin(plugins))]
 
 #![deny(warnings)]