ditch buble, replace uglify with terser

rollup.config.js

@@ -1,8 +1,7 @@
 import svelte from 'rollup-plugin-svelte';
 import resolve from 'rollup-plugin-node-resolve';
 import commonjs from 'rollup-plugin-commonjs';
-import buble from 'rollup-plugin-buble';
-import uglify from 'rollup-plugin-uglify';
+import { terser } from 'rollup-plugin-terser';
 
 const production = !process.env.ROLLUP_WATCH;
 
@@ -38,8 +37,7 @@ export default {
 		commonjs(),
 
 		// If we're building for production (npm run build
-		// instead of npm run dev), transpile and minify
-		production && buble({ include: ['src/**', 'node_modules/svelte/shared.js'] }),
-		production && uglify()
+		// instead of npm run dev), minify
+		production && terser()
 	]
 };