compress text assets for docs, when uploading (#3926)
compress text assets for docs, when uploading (#3926)

* compress text assets for docs, when uploading

* reorder args

* ensure old files are deleted

* recurse on the cp

* set source path correctly

aghassemi/flutter,flutter/flutter,aghassemi/flutter,aghassemi/flutter,flutter/flutter,tvolkert/flutter,tvolkert/flutter,turnidge/flutter,tvolkert/flutter,tvolkert/flutter,flutter/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,cbracken/flutter,Hixie/flutter,cbracken/flutter,Hixie/flutter,flutter/flutter,tvolkert/flutter,tvolkert/flutter,cbracken/flutter,flutter/flutter,Hixie/flutter,cbracken/flutter,tvolkert/flutter,tvolkert/flutter,cbracken/flutter,cbracken/flutter,turnidge/flutter,Hixie/flutter,turnidge/flutter,flutter/flutter,cbracken/flutter,flutter/flutter,turnidge/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter,flutter/flutter,Hixie/flutter,cbracken/flutter,Hixie/flutter,aghassemi/flutter,turnidge/flutter,tvolkert/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter