.gitattributes: treat source maps as binary files
.gitattributes: treat source maps as binary files

BS3 commits: 40961659acf84a8b0952f87e9a46462fac7a7e24

mozillo/todc-bootstrap,2947721120/todc-bootstrap,up2vs/todc-bootstrap,todc/todc-bootstrap,ztx1491/todc-bootstrap,todc/todc-bootstrap,aaroncnhk/todc-bootstrap,2947721120/googlebt4,todc/todc-bootstrap