Use babel instead of buble

This way we can target just the JSX tranformation. We don't use any other cutting edge JS features that require compilation, nor should we in the future.

package.json

@@ -7,6 +7,16 @@
     "email": "feross@webtorrent.io",
     "url": "https://webtorrent.io"
   },
+  "babel": {
+    "plugins": [
+      [
+        "@babel/plugin-transform-react-jsx",
+        {
+          "useBuiltIns": true
+        }
+      ]
+    ]
+  },
   "bugs": {
     "url": "https://github.com/webtorrent/webtorrent-desktop/issues"
   },
@@ -47,6 +57,9 @@
     "winreg": "^1.2.4"
   },
   "devDependencies": {
+    "@babel/cli": "^7.6.0",
+    "@babel/core": "^7.6.0",
+    "@babel/plugin-transform-react-jsx": "^7.3.0",
     "babel-eslint": "^10.1.0",
     "buble": "^0.20.0",
     "cross-zip": "^3.1.0",
@@ -96,7 +109,7 @@
     "url": "git://github.com/webtorrent/webtorrent-desktop.git"
   },
   "scripts": {
-    "build": "buble src --target chrome:71 --output build",
+    "build": "babel src --out-dir build",
     "clean": "node ./bin/clean.js",
     "gh-release": "gh-release",
     "install-system-deps": "brew install fakeroot dpkg rpm",