Bump @babel/core from 7.4.5 to 7.5.4

Bumps [@babel/core](https://github.com/babel/babel) from 7.4.5 to 7.5.4.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](babel/babel@v7.4.5...v7.5.4)

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

package.json

@@ -34,7 +34,7 @@
   "author": "Mozilla",
   "license": "MPL-2.0",
   "dependencies": {
-    "@babel/core": "^7.4.5",
+    "@babel/core": "^7.5.4",
     "@babel/preset-env": "^7.4.5",
     "@babel/preset-react": "^7.0.0",
     "autoprefixer": "^9.6.0",