Always generate source maps for Rollup
Always generate source maps for Rollup

References #1141.

ncave/Fable,fable-compiler/Fable,ncave/Fable,ncave/Fable,fable-compiler/Fable,ncave/Fable,fable-compiler/Fable,inosik/Fable,ncave/Fable,inosik/Fable,fable-compiler/Fable,fable-compiler/Fable,fable-compiler/Fable,ncave/Fable,ncave/Fable,fable-compiler/Fable