Bump @babel/plugin-proposal-class-properties from 7.4.0 to 7.7.0

Bumps [@babel/plugin-proposal-class-properties](https://github.com/babel/babel) from 7.4.0 to 7.7.0.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](babel/babel@v7.4.0...v7.7.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -209,7 +209,7 @@
   },
   "devDependencies": {
     "@babel/core": "^7.4.3",
-    "@babel/plugin-proposal-class-properties": "^7.4.0",
+    "@babel/plugin-proposal-class-properties": "^7.7.0",
     "@babel/plugin-proposal-object-rest-spread": "^7.4.3",
     "@babel/plugin-transform-runtime": "^7.6.2",
     "@babel/preset-env": "^7.4.3",