Fix rollup sourceMap file references (waiting on rollup/rollup#344).

Author: developit

rollup.config.js

@@ -1,6 +1,9 @@
 import babel from 'rollup-plugin-babel';
+import path from 'path';
+import fs from 'fs';
 
 export default {
+	sourceMapFile: path.resolve(JSON.parse(fs.readFileSync('./package.json')).main),
 	plugins: [
 		babel({
 			sourceMap: true