Fix Event#element throwing errors for events missing a currentTarget.
Fix Event#element throwing errors for events missing a currentTarget.

savetheclocktower/prototype,sdumitriu/prototype,sdumitriu/prototype,fashionsun/prototype,erpframework/prototype,fashionsun/prototype,kangax/prototype,sdumitriu/prototype,lamsieuquay/prototype,loduis/prototype,lamsieuquay/prototype,ShefronYudy/prototype,Gargaj/prototype,kangax/prototype,292388900/prototype,Jiasm/prototype,fashionsun/prototype,sstephenson/prototype,baiyanghese/prototype,erpframework/prototype,erpframework/prototype,sstephenson/prototype,savetheclocktower/prototype,sstephenson/prototype,ldf7801528/prototype,baiyanghese/prototype,ridixcr/prototype,Jiasm/prototype,Gargaj/prototype,loduis/prototype,ShefronYudy/prototype,ridixcr/prototype,292388900/prototype,ldf7801528/prototype,292388900/prototype,loduis/prototype,Gargaj/prototype,ldf7801528/prototype,Jiasm/prototype,leafo/prototype,lamsieuquay/prototype,leafo/prototype,ridixcr/prototype,ShefronYudy/prototype