Tex example: Update babel to v7 + other deps (#2533)

Summary:
**Summary**

Updating deps to get rid of all those dependabot PRs. Also was kind of fun to do the whole babel v6 -> babel v7 migration. `npx babel-upgrade --write --install` was pretty handy.

NOTE: I didn't upgrade `katex` to v0.8 because that broke the equation rendering in the example.

**Test Plan**

Ran the example, everything works.

Pull Request resolved: #2533

Reviewed By: joelseq

Differential Revision: D22787662

Pulled By: mrkev

fbshipit-source-id: b177d74b761982a4c6d674e44545312ef4609500

examples/draft-0-10-0/tex/.babelrc

@@ -1 +1 @@
-{ "presets": ["es2015"] }
+{"presets":["@babel/env"]}

examples/draft-0-10-0/tex/package.json

@@ -4,21 +4,21 @@
     "start": "babel-node ./server.js"
   },
   "dependencies": {
-    "babel": "6.0.0",
-    "babel-core": "^6.8.0",
-    "babel-loader": "^7.0.0",
-    "babel-preset-es2015": "^6.9.0",
-    "babel-preset-react": "^6.11.1",
+    "@babel/core": "^7.0.0",
+    "@babel/preset-env": "^7.0.0",
+    "@babel/preset-react": "^7.0.0",
+    "babel-loader": "^8.1.0",
     "draft-js": "file:../../../",
-    "express": "^4.13.1",
+    "express": "^4.17.1",
     "immutable": "^3.7.4",
-    "katex": "^0.5.1",
+    "katex": "^0.7.0",
     "react": "file:../../../node_modules/react",
     "react-dom": "file:../../../node_modules/react-dom",
-    "webpack": "^4.0.0",
-    "webpack-dev-server": "^3.1.14"
+    "webpack": "^4.44.0",
+    "webpack-dev-server": "^3.11.0"
   },
   "devDependencies": {
-    "babel-cli": "^6.18.0"
+    "@babel/cli": "^7.0.0",
+    "@babel/node": "^7.0.0"
   }
 }

examples/draft-0-10-0/tex/server.js

@@ -29,7 +29,7 @@ var compiler = webpack({
         exclude: /node_modules/,
         loader: 'babel-loader',
         options: {
-          presets: ['es2015', 'react'],
+          presets: ['@babel/env', '@babel/react'],
         },
       },
     ],