Upgrade CodeMirror to latest v5

Gruntfile.js

@@ -1,10 +1,12 @@
 /* jshint node:true */
 /* jshint esversion: 6 */
+/* eslint-env es6 */
 /* globals Set */
 var webpackConfig = require( './webpack.config' );
 var installChanged = require( 'install-changed' );
 
 module.exports = function(grunt) {
+	var pkg = grunt.file.readJSON( 'package.json' );
 	var path = require('path'),
 		fs = require( 'fs' ),
 		glob = require( 'glob' ),
@@ -175,6 +177,27 @@ module.exports = function(grunt) {
 				banner: BANNER_TEXT,
 				linebreak: true
 			},
+			codemirror: {
+				options: {
+					linebreak: false,
+					banner: `/*! This file is auto-generated from CodeMirror - v${ pkg.dependencies.codemirror }\n` +
+						`\n` +
+						`CodeMirror, copyright (c) by Marijn Haverbeke and others\n` +
+						`Distributed under an MIT license: http://codemirror.net/LICENSE\n` +
+						`\n` +
+						`This is CodeMirror (http://codemirror.net), a code editor\n` +
+						`implemented in JavaScript on top of the browser's DOM.\n` +
+						`\n` +
+						`You can find some technical background for some of the code below\n` +
+						`at http://marijnhaverbeke.nl/blog/#cm-internals .\n` +
+						`*/`
+				},
+				files: {
+					src: [
+						WORKING_DIR + 'wp-includes/js/codemirror/codemirror.min.css'
+					]
+				}
+			},
 			files: {
 				src: [
 					WORKING_DIR + 'wp-admin/css/*.min.css',
@@ -311,6 +334,33 @@ module.exports = function(grunt) {
 					}
 				]
 			},
+			'codemirror': {
+				options: {
+					process: function( content, srcpath ) {
+						if ( srcpath.indexOf( 'htmlhint.min.js' ) !== -1 ) {
+							return content + '\nif ( window.HTMLHint && window.HTMLHint.HTMLHint ) { window.HTMLHint = window.HTMLHint.HTMLHint; }';
+						}
+						return content;
+					}
+				},
+				files: [
+					{
+						[ WORKING_DIR + 'wp-includes/js/codemirror/csslint.js' ]: [ './node_modules/csslint/dist/csslint.js' ],
+						[ WORKING_DIR + 'wp-includes/js/codemirror/esprima.js' ]: [ './node_modules/esprima/dist/esprima.js' ],
+						[ WORKING_DIR + 'wp-includes/js/codemirror/htmlhint.js' ]: [ './node_modules/htmlhint/dist/htmlhint.min.js' ],
+						[ WORKING_DIR + 'wp-includes/js/codemirror/jsonlint.js' ]: [ './node_modules/jsonlint/web/jsonlint.js' ],
+					},
+					{
+						expand: true,
+						cwd: SOURCE_DIR + 'js/_enqueues/vendor/codemirror/',
+						src: [
+							'fakejshint.js',
+							'htmlhint-kses.js',
+						],
+						dest: WORKING_DIR + 'wp-includes/js/codemirror/'
+					}
+				]
+			},
 			'vendor-js': {
 				files: [
 					{
@@ -562,6 +612,22 @@ module.exports = function(grunt) {
 			options: {
 				compatibility: 'ie11'
 			},
+			codemirror: {
+				files: {
+					[ WORKING_DIR + 'wp-includes/js/codemirror/codemirror.min.css' ]: [
+						'node_modules/codemirror/lib/codemirror.css',
+						'node_modules/codemirror/addon/hint/show-hint.css',
+						'node_modules/codemirror/addon/lint/lint.css',
+						'node_modules/codemirror/addon/dialog/dialog.css',
+						'node_modules/codemirror/addon/display/fullscreen.css',
+						'node_modules/codemirror/addon/fold/foldgutter.css',
+						'node_modules/codemirror/addon/merge/merge.css',
+						'node_modules/codemirror/addon/scroll/simplescrollbars.css',
+						'node_modules/codemirror/addon/search/matchesonscrollbar.css',
+						'node_modules/codemirror/addon/tern/tern.css'
+					]
+				}
+			},
 			core: {
 				expand: true,
 				cwd: WORKING_DIR,
@@ -921,7 +987,8 @@ module.exports = function(grunt) {
 		webpack: {
 			prod: webpackConfig( { environment: 'production', buildTarget: WORKING_DIR } ),
 			dev: webpackConfig( { environment: 'development', buildTarget: WORKING_DIR } ),
-			watch: webpackConfig( { environment: 'development', watch: true } )
+			watch: webpackConfig( { environment: 'development', watch: true } ),
+			codemirror: require( './tools/webpack/codemirror.config.js' )( { buildTarget: WORKING_DIR } ),
 		},
 		concat: {
 			tinymce: {
@@ -1652,6 +1719,13 @@ module.exports = function(grunt) {
 		'uglify:moment'
 	] );
 
+	grunt.registerTask( 'build:codemirror', [
+		'webpack:codemirror',
+		'cssmin:codemirror',
+		'usebanner:codemirror',
+		'copy:codemirror'
+	] );
+
 	grunt.registerTask( 'build:webpack', [
 		'clean:webpack-assets',
 		'webpack:prod',
@@ -1902,6 +1976,7 @@ module.exports = function(grunt) {
 			grunt.task.run( [
 				'build:js',
 				'build:css',
+				'build:codemirror',
 				'gutenberg-sync',
 				'gutenberg-copy',
 				'copy-vendor-scripts',
@@ -1913,6 +1988,7 @@ module.exports = function(grunt) {
 				'build:files',
 				'build:js',
 				'build:css',
+				'build:codemirror',
 				'gutenberg-sync',
 				'gutenberg-copy',
 				'copy-vendor-scripts',