Twenty Nineteen: Update several devDependencies.

This updates the following dependencies:
- `@wordpress/browserslist-config` from `2.7.0` to `3.0.0`.
- `autoprefixer` from `9.8.5` to `9.8.6`.
- `node-sass` from `4.14.1` to `5.0.0`.
- `postcss-cli` from `7.1.1` to `7.1.2`.
- `postcss-focus-within` from `3.0.0` to `4.0.0`.
- `rtlcss` from `2.5.0` to `2.6.2`.

There are no changes after running `build`.

See #51801.

git-svn-id: https://develop.svn.wordpress.org/trunk@50081 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-content/themes/twentynineteen/package.json

@@ -7,14 +7,14 @@
   },
   "homepage": "https://github.com/WordPress/twentynineteen#readme",
   "devDependencies": {
-    "@wordpress/browserslist-config": "^2.7.0",
-    "autoprefixer": "^9.8.5",
+    "@wordpress/browserslist-config": "^3.0.0",
+    "autoprefixer": "^9.8.6",
     "chokidar-cli": "^2.1.0",
-    "node-sass": "^4.14.1",
+    "node-sass": "^5.0.0",
     "npm-run-all": "^4.1.5",
-    "postcss-cli": "^7.0.0",
-    "postcss-focus-within": "^3.0.0",
-    "rtlcss": "^2.5.0"
+    "postcss-cli": "^7.1.2",
+    "postcss-focus-within": "^4.0.0",
+    "rtlcss": "^2.6.2"
   },
   "rtlcssConfig": {
     "options": {