当path为空的时候就会报错，跑不下去了
当path为空的时候就会报错，跑不下去了

path为空的场景是将seajs源码以内联形式输出输出的时候，其script的src属性为""。
跑到这里的时候便会报错
https://github.com/seajs/seajs/blob/master/src/util-path.js#L176

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