Add babel plugin for rollup & transform code (#6555)

* Add babel plugin for rollup & transform code
* Add .browserlistrc file & copy defaults

.babelrc

@@ -0,0 +1,3 @@
+{
+  "presets": ["@babel/preset-env"]
+}

.browserlistrc

@@ -0,0 +1,4 @@
+> 0.5%
+last 2 versions
+Firefox ESR
+not dead

package.json

@@ -29,6 +29,9 @@
     "dist/*.js"
   ],
   "devDependencies": {
+    "@babel/core": "^7.6.2",
+    "@babel/preset-env": "^7.6.2",
+    "babel-preset-es2015-rollup": "^3.0.0",
     "clean-css": "^4.2.1",
     "coveralls": "^3.0.0",
     "eslint": "^5.9.0",
@@ -56,6 +59,7 @@
     "merge-stream": "^1.0.1",
     "pixelmatch": "^4.0.2",
     "rollup": "^1.0.0",
+    "rollup-plugin-babel": "^4.3.3",
     "rollup-plugin-commonjs": "^10.0.0",
     "rollup-plugin-istanbul": "^2.0.1",
     "rollup-plugin-node-resolve": "^5.0.0",

rollup.config.js

@@ -2,6 +2,7 @@
 
 const commonjs = require('rollup-plugin-commonjs');
 const resolve = require('rollup-plugin-node-resolve');
+const babel = require('rollup-plugin-babel');
 const terser = require('rollup-plugin-terser').terser;
 const optional = require('./rollup.plugins').optional;
 const stylesheet = require('./rollup.plugins').stylesheet;
@@ -24,6 +25,9 @@ module.exports = [
 		plugins: [
 			resolve(),
 			commonjs(),
+			babel({
+				exclude: 'node_modules/**'
+			}),
 			stylesheet({
 				extract: true
 			}),
@@ -50,6 +54,9 @@ module.exports = [
 		plugins: [
 			resolve(),
 			commonjs(),
+			babel({
+				exclude: 'node_modules/**'
+			}),
 			optional({
 				include: ['moment']
 			}),
@@ -85,6 +92,9 @@ module.exports = [
 		plugins: [
 			resolve(),
 			commonjs(),
+			babel({
+				exclude: 'node_modules/**'
+			}),
 			stylesheet()
 		],
 		output: {
@@ -100,6 +110,9 @@ module.exports = [
 		plugins: [
 			resolve(),
 			commonjs(),
+			babel({
+				exclude: 'node_modules/**'
+			}),
 			stylesheet({
 				minify: true
 			}),