[7.0] remove standalone babel package (#5293)

Having it isn't compatible with the changes for `babel-cli -> @babel/cli`

packages/babel/.npmignore

@@ -1,3 +0,0 @@
-src
-test
-node_modules

packages/babel/README.md

@@ -1 +0,0 @@
-# babel

packages/babel/index.js

@@ -1 +0,0 @@
-throw new Error("The node API for `babel` has been moved to `babel-core`.");

packages/babel/package.json

@@ -1,14 +0,0 @@
-{
-  "name": "babel",
-  "version": "6.5.2",
-  "description": "Turn ES6 code into readable vanilla ES5 with source maps",
-  "author": "Sebastian McKenzie <sebmck@gmail.com>",
-  "homepage": "https://babeljs.io/",
-  "license": "MIT",
-  "repository": "https://github.com/babel/babel/tree/master/packages/babel",
-  "bin": {
-    "babel": "./lib/cli.js",
-    "babel-node": "./lib/cli.js",
-    "babel-external-helpers": "./lib/cli.js"
-  }
-}

packages/babel/src/cli.js

@@ -1,13 +0,0 @@
-#!/usr/bin/env node
-import path from "path";
-
-const globalMessage = path.dirname(process.execPath) === path.dirname(process.env._ || "") ? " -g" : "";
-
-console.error("You have mistakenly installed the `babel` package, which is a no-op in Babel 6.\n" +
-  "Babel's CLI commands have been moved from the `babel` package to the `babel-cli` package.\n" +
-  "\n" +
-  "    npm uninstall" + globalMessage + " babel\n" +
-  "    npm install --save-dev babel-cli\n" +
-  "\n" +
-  "See http://babeljs.io/docs/usage/cli/ for setup instructions.");
-process.exit(1);