__proto__ not supported in IE9, IE10
To reproduce open https://buble.surge.sh/ in IE10 and get the following: Object doesn't support property or method 'initialise'
https://gitlab.com/Rich-Harris/buble/blob/master/src/program/Program.js#L22
In src/program/Program.js
This line this.body.initialise( transforms );
// throws Object doesn't support property or method 'initialise'