Make the second argument to HTMLSelectElement.add optional.
Make the second argument to HTMLSelectElement.add optional.

While working on landing https://github.com/google/closure-compiler/pull/1755 I found several places where people are omitting the second argument, but we weren't catching it because the receiver was just typed as Element rather than HTMLSelectElement. In order to get the compiler to accept calls to elem.remove(someNumber), we have to change the type to HTMLSelectElement which reveals the "error" (not actually an error, once this CL lands).
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monetate/closure-compiler,redforks/closure-compiler,MatrixFrog/closure-compiler,Medium/closure-compiler,tdelmas/closure-compiler,mprobst/closure-compiler,mprobst/closure-compiler,shantanusharma/closure-compiler,vobruba-martin/closure-compiler,GerHobbelt/closure-compiler,tiobe/closure-compiler,brad4d/closure-compiler,GerHobbelt/closure-compiler,tiobe/closure-compiler,Pimm/closure-compiler,LorenzoDV/closure-compiler,Yannic/closure-compiler,google/closure-compiler,anomaly/closure-compiler,google/closure-compiler,Yannic/closure-compiler,ChadKillingsworth/closure-compiler,monetate/closure-compiler,monetate/closure-compiler,Dominator008/closure-compiler,tdelmas/closure-compiler,superkonduktr/closure-compiler,vobruba-martin/closure-compiler,google/closure-compiler,tiobe/closure-compiler,shantanusharma/closure-compiler,monetate/closure-compiler,LorenzoDV/closure-compiler,GerHobbelt/closure-compiler,MatrixFrog/closure-compiler,nawawi/closure-compiler,superkonduktr/closure-compiler,MatrixFrog/closure-compiler,tdelmas/closure-compiler,brad4d/closure-compiler,redforks/closure-compiler,Yannic/closure-compiler,ChadKillingsworth/closure-compiler,nawawi/closure-compiler,Medium/closure-compiler,Pimm/closure-compiler,anomaly/closure-compiler,MatrixFrog/closure-compiler,tiobe/closure-compiler,shantanusharma/closure-compiler,nawawi/closure-compiler,mprobst/closure-compiler,LorenzoDV/closure-compiler,superkonduktr/closure-compiler,vobruba-martin/closure-compiler,Medium/closure-compiler,ChadKillingsworth/closure-compiler,vobruba-martin/closure-compiler,mprobst/closure-compiler,redforks/closure-compiler,GerHobbelt/closure-compiler,Yannic/closure-compiler,superkonduktr/closure-compiler,Dominator008/closure-compiler,google/closure-compiler,shantanusharma/closure-compiler,ChadKillingsworth/closure-compiler,Pimm/closure-compiler,anomaly/closure-compiler,tdelmas/closure-compiler,Dominator008/closure-compiler,brad4d/closure-compiler,anomaly/closure-compiler,nawawi/closure-compiler