Fix bootstrap: global should be this, not window
Fix bootstrap: global should be this, not window

In a javascript context, all JS function are not all attached to the window object.
This is the case of 'native' functions. In SlimerJS, the 'require' function is
not attached to the window object. It is a standalone function.

mickaelandrieu/casperjs,mcwonka/casperjs,pbrazdil/casperjs,pbrazdil/casperjs,kyroskoh/casperjs,vietch2612/casperjs,muntasir2000/casperjs,alexbiehl/casperjs,JZL/casperjs,vladikoff/casperjs,casperjs/casperjs,artillery/casperjs,hexid/casperjs,sircelsiussexy/casperjs,jjyycchh/casperjs,casperjs/casperjs,linkedin/casperjs,RobertoMalatesta/casperjs,joshuafcole/casperjs,HienLeThi/Casperjs_Demo,mickaelandrieu/casperjs,soundyogi/casperjs,kyroskoh/casperjs,JZL/casperjs,ravindrasingh22/casperjs,hudl/casperjs,vladikoff/casperjs,jjyycchh/casperjs,RobertoMalatesta/casperjs,JZL/casperjs,singhdev/casperjs,davidwhthomas/casperjs,hexid/casperjs,jefleponot/casperjs,soundyogi/casperjs,flyHe/casperjs,mcwonka/casperjs,joshuafcole/casperjs,jefleponot/casperjs,istr/casperjs,artillery/casperjs,RobertoMalatesta/casperjs,ravindrasingh22/casperjs,hlr1983/casperjs,artillery/casperjs,jamesanthonyferguson/casperjs,muntasir2000/casperjs,Andrey-Pavlov/casperjs,kyroskoh/casperjs,jefleponot/casperjs,hudl/casperjs,davidwhthomas/casperjs,hexid/casperjs,sircelsiussexy/casperjs,jjyycchh/casperjs,pbrazdil/casperjs,mickaelandrieu/casperjs,Andrey-Pavlov/casperjs,artillery/casperjs,n1k0/casperjs,jamesanthonyferguson/casperjs,n1k0/casperjs,ravindrasingh22/casperjs,artillery/casperjs,JZL/casperjs,vietch2612/casperjs,PeterWangPo/casperjs,HienLeThi/Casperjs_Demo,artillery/casperjs,PeterWangPo/casperjs,hlr1983/casperjs,alexbiehl/casperjs,jamesanthonyferguson/casperjs,istr/casperjs,hexid/casperjs,casperjs/casperjs,n1k0/casperjs,flyHe/casperjs,muntasir2000/casperjs,cryptoquick/casperjs,hexid/casperjs,casperjs/casperjs,kyroskoh/casperjs,alexbiehl/casperjs,linkedin/casperjs,istr/casperjs,singhdev/casperjs,flyHe/casperjs,singhdev/casperjs,soundyogi/casperjs,davidwhthomas/casperjs,joshuafcole/casperjs,linkedin/casperjs,sircelsiussexy/casperjs,flyHe/casperjs,hexid/casperjs,davidwhthomas/casperjs,jefleponot/casperjs,HienLeThi/Casperjs_Demo,linkedin/casperjs,n1k0/casperjs,dj31416/casperjs,hlr1983/casperjs,Andrey-Pavlov/casperjs,Andrey-Pavlov/casperjs,cryptoquick/casperjs,davidwhthomas/casperjs,dj31416/casperjs,vietch2612/casperjs,HienLeThi/Casperjs_Demo,hudl/casperjs,dj31416/casperjs,joshuafcole/casperjs,Andrey-Pavlov/casperjs,n1k0/casperjs,PeterWangPo/casperjs,jamesanthonyferguson/casperjs,linkedin/casperjs,istr/casperjs,casperjs/casperjs,sircelsiussexy/casperjs,jjyycchh/casperjs,vietch2612/casperjs,pbrazdil/casperjs,mickaelandrieu/casperjs,vladikoff/casperjs,kyroskoh/casperjs,hlr1983/casperjs,RobertoMalatesta/casperjs,dj31416/casperjs,muntasir2000/casperjs,HienLeThi/Casperjs_Demo,joshuafcole/casperjs,mickaelandrieu/casperjs,ravindrasingh22/casperjs,JZL/casperjs,alexbiehl/casperjs,mickaelandrieu/casperjs,mcwonka/casperjs,mcwonka/casperjs,istr/casperjs,kyroskoh/casperjs,alexbiehl/casperjs,PeterWangPo/casperjs,vietch2612/casperjs,cryptoquick/casperjs,jamesanthonyferguson/casperjs,soundyogi/casperjs,sircelsiussexy/casperjs,mcwonka/casperjs,mcwonka/casperjs,casperjs/casperjs,sircelsiussexy/casperjs,Andrey-Pavlov/casperjs,flyHe/casperjs,muntasir2000/casperjs,soundyogi/casperjs,singhdev/casperjs,cryptoquick/casperjs,PeterWangPo/casperjs,n1k0/casperjs,davidwhthomas/casperjs,jefleponot/casperjs,alexbiehl/casperjs,JZL/casperjs,hudl/casperjs,pbrazdil/casperjs,jamesanthonyferguson/casperjs,cryptoquick/casperjs,hlr1983/casperjs,vladikoff/casperjs,jefleponot/casperjs,dj31416/casperjs,vladikoff/casperjs,pbrazdil/casperjs,ravindrasingh22/casperjs,istr/casperjs,flyHe/casperjs,linkedin/casperjs,cryptoquick/casperjs,hlr1983/casperjs,RobertoMalatesta/casperjs,muntasir2000/casperjs,HienLeThi/Casperjs_Demo,dj31416/casperjs,vietch2612/casperjs,singhdev/casperjs,hudl/casperjs,jjyycchh/casperjs,jjyycchh/casperjs,ravindrasingh22/casperjs,RobertoMalatesta/casperjs,soundyogi/casperjs,joshuafcole/casperjs,PeterWangPo/casperjs