[Extensions] Add support for persistent callback listener
[Extensions] Add support for persistent callback listener

This is going to be the base of the EventTarget implementation. It is
important to remove the listener at some point otherwise the object will
leak.

hgl888/crosswalk,zeropool/crosswalk,jpike88/crosswalk,TheDirtyCalvinist/spacewalk,rakuco/crosswalk,TheDirtyCalvinist/spacewalk,heke123/crosswalk,bestwpw/crosswalk,dreamsxin/crosswalk,tedshroyer/crosswalk,fujunwei/crosswalk,minggangw/crosswalk,zliang7/crosswalk,heke123/crosswalk,pk-sam/crosswalk,amaniak/crosswalk,bestwpw/crosswalk,lincsoon/crosswalk,Bysmyyr/crosswalk,jondong/crosswalk,hgl888/crosswalk-efl,crosswalk-project/crosswalk-efl,Bysmyyr/crosswalk,marcuspridham/crosswalk,jondong/crosswalk,weiyirong/crosswalk-1,fujunwei/crosswalk,crosswalk-project/crosswalk-efl,rakuco/crosswalk,jpike88/crosswalk,alex-zhang/crosswalk,bestwpw/crosswalk,rakuco/crosswalk,ZhengXinCN/crosswalk,hgl888/crosswalk-efl,huningxin/crosswalk,marcuspridham/crosswalk,darktears/crosswalk,stonegithubs/crosswalk,siovene/crosswalk,fujunwei/crosswalk,dreamsxin/crosswalk,baleboy/crosswalk,crosswalk-project/crosswalk-efl,seanlong/crosswalk,zeropool/crosswalk,DonnaWuDongxia/crosswalk,hgl888/crosswalk-efl,Bysmyyr/crosswalk,xzhan96/crosswalk,jondwillis/crosswalk,alex-zhang/crosswalk,siovene/crosswalk,wuhengzhi/crosswalk,mrunalk/crosswalk,weiyirong/crosswalk-1,wuhengzhi/crosswalk,siovene/crosswalk,pk-sam/crosswalk,lincsoon/crosswalk,jondwillis/crosswalk,xzhan96/crosswalk,XiaosongWei/crosswalk,jondong/crosswalk,leonhsl/crosswalk,TheDirtyCalvinist/spacewalk,ZhengXinCN/crosswalk,rakuco/crosswalk,jondwillis/crosswalk,DonnaWuDongxia/crosswalk,Pluto-tv/crosswalk,crosswalk-project/crosswalk,darktears/crosswalk,chuan9/crosswalk,siovene/crosswalk,stonegithubs/crosswalk,DonnaWuDongxia/crosswalk,hgl888/crosswalk,mrunalk/crosswalk,XiaosongWei/crosswalk,myroot/crosswalk,shaochangbin/crosswalk,leonhsl/crosswalk,jondong/crosswalk,lincsoon/crosswalk,stonegithubs/crosswalk,RafuCater/crosswalk,jondwillis/crosswalk,Bysmyyr/crosswalk,PeterWangIntel/crosswalk,ZhengXinCN/crosswalk,seanlong/crosswalk,tedshroyer/crosswalk,chinakids/crosswalk,dreamsxin/crosswalk,tedshroyer/crosswalk,wuhengzhi/crosswalk,baleboy/crosswalk,jondong/crosswalk,myroot/crosswalk,heke123/crosswalk,amaniak/crosswalk,darktears/crosswalk,baleboy/crosswalk,zliang7/crosswalk,rakuco/crosswalk,minggangw/crosswalk,chuan9/crosswalk,RafuCater/crosswalk,xzhan96/crosswalk,pk-sam/crosswalk,crosswalk-project/crosswalk-efl,tomatell/crosswalk,PeterWangIntel/crosswalk,zliang7/crosswalk,stonegithubs/crosswalk,TheDirtyCalvinist/spacewalk,alex-zhang/crosswalk,siovene/crosswalk,minggangw/crosswalk,tomatell/crosswalk,baleboy/crosswalk,PeterWangIntel/crosswalk,lincsoon/crosswalk,PeterWangIntel/crosswalk,shaochangbin/crosswalk,seanlong/crosswalk,hgl888/crosswalk-efl,Bysmyyr/crosswalk,leonhsl/crosswalk,stonegithubs/crosswalk,jpike88/crosswalk,dreamsxin/crosswalk,stonegithubs/crosswalk,Pluto-tv/crosswalk,Pluto-tv/crosswalk,mrunalk/crosswalk,jpike88/crosswalk,alex-zhang/crosswalk,myroot/crosswalk,zeropool/crosswalk,chinakids/crosswalk,Pluto-tv/crosswalk,jondwillis/crosswalk,crosswalk-project/crosswalk,heke123/crosswalk,heke123/crosswalk,fujunwei/crosswalk,marcuspridham/crosswalk,Pluto-tv/crosswalk,darktears/crosswalk,rakuco/crosswalk,PeterWangIntel/crosswalk,axinging/crosswalk,DonnaWuDongxia/crosswalk,PeterWangIntel/crosswalk,RafuCater/crosswalk,XiaosongWei/crosswalk,shaochangbin/crosswalk,marcuspridham/crosswalk,huningxin/crosswalk,crosswalk-project/crosswalk,hgl888/crosswalk,Bysmyyr/crosswalk,alex-zhang/crosswalk,zeropool/crosswalk,RafuCater/crosswalk,Pluto-tv/crosswalk,qjia7/crosswalk,leonhsl/crosswalk,seanlong/crosswalk,crosswalk-project/crosswalk,fujunwei/crosswalk,zliang7/crosswalk,bestwpw/crosswalk,pk-sam/crosswalk,TheDirtyCalvinist/spacewalk,amaniak/crosswalk,fujunwei/crosswalk,qjia7/crosswalk,baleboy/crosswalk,hgl888/crosswalk,crosswalk-project/crosswalk-efl,bestwpw/crosswalk,siovene/crosswalk,marcuspridham/crosswalk,mrunalk/crosswalk,chinakids/crosswalk,rakuco/crosswalk,xzhan96/crosswalk,minggangw/crosswalk,hgl888/crosswalk,crosswalk-project/crosswalk-efl,leonhsl/crosswalk,shaochangbin/crosswalk,jpike88/crosswalk,bestwpw/crosswalk,siovene/crosswalk,hgl888/crosswalk-efl,dreamsxin/crosswalk,crosswalk-project/crosswalk,jondong/crosswalk,mrunalk/crosswalk,chinakids/crosswalk,qjia7/crosswalk,marcuspridham/crosswalk,tedshroyer/crosswalk,chuan9/crosswalk,axinging/crosswalk,hgl888/crosswalk-efl,weiyirong/crosswalk-1,seanlong/crosswalk,DonnaWuDongxia/crosswalk,tedshroyer/crosswalk,darktears/crosswalk,amaniak/crosswalk,pk-sam/crosswalk,xzhan96/crosswalk,minggangw/crosswalk,RafuCater/crosswalk,stonegithubs/crosswalk,RafuCater/crosswalk,ZhengXinCN/crosswalk,qjia7/crosswalk,xzhan96/crosswalk,marcuspridham/crosswalk,Bysmyyr/crosswalk,qjia7/crosswalk,darktears/crosswalk,fujunwei/crosswalk,minggangw/crosswalk,weiyirong/crosswalk-1,crosswalk-project/crosswalk,zeropool/crosswalk,baleboy/crosswalk,rakuco/crosswalk,zliang7/crosswalk,amaniak/crosswalk,jondong/crosswalk,RafuCater/crosswalk,lincsoon/crosswalk,chuan9/crosswalk,marcuspridham/crosswalk,Pluto-tv/crosswalk,dreamsxin/crosswalk,leonhsl/crosswalk,jpike88/crosswalk,dreamsxin/crosswalk,darktears/crosswalk,pk-sam/crosswalk,axinging/crosswalk,tedshroyer/crosswalk,ZhengXinCN/crosswalk,Bysmyyr/crosswalk,wuhengzhi/crosswalk,zeropool/crosswalk,amaniak/crosswalk,XiaosongWei/crosswalk,weiyirong/crosswalk-1,zliang7/crosswalk,XiaosongWei/crosswalk,XiaosongWei/crosswalk,axinging/crosswalk,crosswalk-project/crosswalk,amaniak/crosswalk,baleboy/crosswalk,leonhsl/crosswalk,huningxin/crosswalk,weiyirong/crosswalk-1,chuan9/crosswalk,hgl888/crosswalk,darktears/crosswalk,xzhan96/crosswalk,heke123/crosswalk,bestwpw/crosswalk,DonnaWuDongxia/crosswalk,shaochangbin/crosswalk,lincsoon/crosswalk,axinging/crosswalk,heke123/crosswalk,tomatell/crosswalk,huningxin/crosswalk,myroot/crosswalk,mrunalk/crosswalk,jondwillis/crosswalk,weiyirong/crosswalk-1,jondong/crosswalk,minggangw/crosswalk,myroot/crosswalk,zliang7/crosswalk,lincsoon/crosswalk,chinakids/crosswalk,hgl888/crosswalk-efl,axinging/crosswalk,tomatell/crosswalk,hgl888/crosswalk,hgl888/crosswalk,zeropool/crosswalk,zliang7/crosswalk,jondwillis/crosswalk,huningxin/crosswalk,huningxin/crosswalk,axinging/crosswalk,shaochangbin/crosswalk,minggangw/crosswalk,tomatell/crosswalk,tomatell/crosswalk,alex-zhang/crosswalk,wuhengzhi/crosswalk,tomatell/crosswalk,XiaosongWei/crosswalk,alex-zhang/crosswalk,DonnaWuDongxia/crosswalk,heke123/crosswalk,ZhengXinCN/crosswalk,TheDirtyCalvinist/spacewalk,ZhengXinCN/crosswalk,crosswalk-project/crosswalk-efl,crosswalk-project/crosswalk,seanlong/crosswalk,chinakids/crosswalk,chuan9/crosswalk,jpike88/crosswalk,qjia7/crosswalk,chuan9/crosswalk,wuhengzhi/crosswalk,lincsoon/crosswalk,PeterWangIntel/crosswalk,baleboy/crosswalk,tedshroyer/crosswalk,myroot/crosswalk,pk-sam/crosswalk,xzhan96/crosswalk