Fix a bug in IE6-8
Fix a bug in IE6-8

MrZhengliang/seajs,121595113/seajs,mosoft521/seajs,FrankElean/SeaJS,LzhElite/seajs,JeffLi1993/seajs,jishichang/seajs,zaoli/seajs,Gatsbyy/seajs,coolyhx/seajs,FrankElean/SeaJS,PUSEN/seajs,lee-my/seajs,chinakids/seajs,lee-my/seajs,mosoft521/seajs,treejames/seajs,judastree/seajs,yern/seajs,lovelykobe/seajs,imcys/seajs,eleanors/SeaJS,longze/seajs,eleanors/SeaJS,wenber/seajs,kaijiemo/seajs,treejames/seajs,LzhElite/seajs,treejames/seajs,angelLYK/seajs,angelLYK/seajs,moccen/seajs,AlvinWei1024/seajs,judastree/seajs,JeffLi1993/seajs,angelLYK/seajs,twoubt/seajs,baiduoduo/seajs,seajs/seajs,coolyhx/seajs,JeffLi1993/seajs,Gatsbyy/seajs,miusuncle/seajs,FrankElean/SeaJS,lovelykobe/seajs,yern/seajs,sheldonzf/seajs,twoubt/seajs,imcys/seajs,zwh6611/seajs,twoubt/seajs,AlvinWei1024/seajs,ysxlinux/seajs,hbdrawn/seajs,Gatsbyy/seajs,kuier/seajs,baiduoduo/seajs,ysxlinux/seajs,ysxlinux/seajs,yuhualingfeng/seajs,jishichang/seajs,liupeng110112/seajs,judastree/seajs,chinakids/seajs,lianggaolin/seajs,PUSEN/seajs,13693100472/seajs,baiduoduo/seajs,Lyfme/seajs,moccen/seajs,kaijiemo/seajs,sheldonzf/seajs,evilemon/seajs,miusuncle/seajs,yuhualingfeng/seajs,evilemon/seajs,longze/seajs,longze/seajs,zwh6611/seajs,evilemon/seajs,coolyhx/seajs,zaoli/seajs,kaijiemo/seajs,lee-my/seajs,uestcNaldo/seajs,hbdrawn/seajs,kuier/seajs,wenber/seajs,121595113/seajs,yern/seajs,eleanors/SeaJS,zwh6611/seajs,MrZhengliang/seajs,moccen/seajs,uestcNaldo/seajs,Lyfme/seajs,Lyfme/seajs,seajs/seajs,liupeng110112/seajs,MrZhengliang/seajs,imcys/seajs,zaoli/seajs,AlvinWei1024/seajs,uestcNaldo/seajs,seajs/seajs,lianggaolin/seajs,tonny-zhang/seajs,13693100472/seajs,sheldonzf/seajs,jishichang/seajs,yuhualingfeng/seajs,miusuncle/seajs,kuier/seajs,mosoft521/seajs,lovelykobe/seajs,tonny-zhang/seajs,wenber/seajs,liupeng110112/seajs,tonny-zhang/seajs,LzhElite/seajs,PUSEN/seajs,lianggaolin/seajs