Babel plugins: remove outdated proposals (#1074)

* Babel plugins: remove outdated proposals

- Also updates the browserlist to be more succint.
- Also migrates from rollup-plugin-babel --> @rollup/plugin-babel

* Update rollup.plugins.js

* revert browserlist jic

config/rollup.plugins.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import babel from 'rollup-plugin-babel';
+import babel from '@rollup/plugin-babel';
 import MagicString from 'magic-string';
 import fs from 'fs';
 import * as path from 'path';
@@ -32,6 +32,7 @@ export function babelPlugin({ transpileToES5, allowConsole = false, allowPostMes
   const exclude = allowConsole ? ['error', 'warn', 'trace', 'info', 'log', 'time', 'timeEnd'] : [];
 
   return babel({
+    babelHelpers: 'bundled',
     exclude: 'node_modules/**',
     presets: [
       [
@@ -45,8 +46,6 @@ export function babelPlugin({ transpileToES5, allowConsole = false, allowPostMes
       ],
     ],
     plugins: [
-      ['@babel/plugin-proposal-object-rest-spread'],
-      ['@babel/proposal-class-properties'],
       [
         'babel-plugin-minify-replace',
         {

package.json

@@ -41,9 +41,8 @@
     "@ampproject/rollup-plugin-closure-compiler": "0.26.0",
     "@babel/cli": "7.14.5",
     "@babel/core": "7.14.6",
-    "@babel/plugin-proposal-class-properties": "7.14.5",
-    "@babel/plugin-proposal-object-rest-spread": "7.14.7",
     "@babel/preset-env": "7.14.7",
+    "@rollup/plugin-babel": "5.3.0",
     "@rollup/plugin-replace": "2.4.2",
     "@types/node": "14.17.3",
     "@types/sinon": "10.0.2",