Fixes #354: remove unnecessary legacy Polymer code from polyfills.
Fixes #354: remove unnecessary legacy Polymer code from polyfills.

bjlxj2008/webcomponentsjs,chiefcll/webcomponentsjs,tuespetre/webcomponentsjs,bjlxj2008/webcomponentsjs,Kureev/webcomponentsjs,callumlocke/webcomponentsjs,tuespetre/webcomponentsjs,tanzhihang/webcomponentsjs,webcomponents/polyfills,tuespetre/webcomponentsjs,uniqname/webcomponentsjs,azogheb/webcomponentsjs,chiefcll/webcomponentsjs,webcomponents/polyfills,cpboyd/webcomponentsjs,jre-g/webcomponentsjs,jre-g/webcomponentsjs,tachyon1337/webcomponentsjs,nirdeshdwa/webcomponentsjs,nirdeshdwa/webcomponentsjs,Kureev/webcomponentsjs,callumlocke/webcomponentsjs,chiefcll/webcomponentsjs,tanzhihang/webcomponentsjs,tanzhihang/webcomponentsjs,cpboyd/webcomponentsjs,uniqname/webcomponentsjs,Kureev/webcomponentsjs,azogheb/webcomponentsjs,webcomponents/polyfills,callumlocke/webcomponentsjs,bjlxj2008/webcomponentsjs,nirdeshdwa/webcomponentsjs,uniqname/webcomponentsjs,cpboyd/webcomponentsjs,tachyon1337/webcomponentsjs,tachyon1337/webcomponentsjs,azogheb/webcomponentsjs,jre-g/webcomponentsjs