strict mode compatibility

This fixes qunitjs#1557 by adopting [globalThis](https://github.com/tc39/proposal-global), and polyfilling it for environments that don't implement it yet via `@ungap/global-this`.

.eslintrc.json

@@ -32,6 +32,9 @@
         "rest-spread-spacing": ["error", "never"],
         "wrap-iife": ["error", "any"]
     },
+	"globals": {
+		"globalThis": true
+	},
     "ignorePatterns": [
         "__codeorigin/**",
         "coverage/**",

package.json

@@ -50,6 +50,7 @@
     "@babel/core": "^7.11.1",
     "@babel/plugin-external-helpers": "^7.10.4",
     "@babel/preset-env": "^7.11.0",
+    "@ungap/global-this": "^0.4.4",
     "coveralls": "^3.1.0",
     "eslint-config-jquery": "^3.0.0",
     "eslint-plugin-html": "^6.1.1",

rollup.config.js

@@ -40,10 +40,6 @@ module.exports = {
 				__dirname + "/src/html-reporter/es6-map.js",
 				"utf8"
 			).toString().trim();
-		},
-
-		globals: {
-			global: "(function() { return this; }())"
 		}
 	},
 	plugins: [
@@ -57,8 +53,5 @@ module.exports = {
 			babelHelpers: "bundled",
 			babelrc: true
 		} )
-	],
-	external: [
-		"global"
 	]
 };

src/core.js

@@ -1,3 +1,4 @@
+import "@ungap/global-this";
 import { window, document, setTimeout } from "./globals";
 
 import equiv from "./equiv";

src/export.js

@@ -1,6 +1,5 @@
 /* global module, exports, define */
 import { window, document, self } from "./globals";
-import global from "global";
 
 export default function exportQUnit( QUnit ) {
 	let exportedModule = false;
@@ -54,6 +53,6 @@ export default function exportQUnit( QUnit ) {
 	// For other environments, such as SpiderMonkey (mozjs) and other
 	// embedded JavaScript engines
 	if ( !exportedModule ) {
-		global.QUnit = QUnit;
+		globalThis.QUnit = QUnit;
 	}
 }

src/globals.js

@@ -1,20 +1,18 @@
-import global from "global";
-
-export const window = global.window;
-export const self = global.self;
-export const console = global.console;
-export const setTimeout = global.setTimeout;
-export const clearTimeout = global.clearTimeout;
+export const window = globalThis.window;
+export const self = globalThis.self;
+export const console = globalThis.console;
+export const setTimeout = globalThis.setTimeout;
+export const clearTimeout = globalThis.clearTimeout;
 
 export const document = window && window.document;
 export const navigator = window && window.navigator;
 
 export const localSessionStorage = ( function() {
 	const x = "qunit-test-string";
 	try {
-		global.sessionStorage.setItem( x, x );
-		global.sessionStorage.removeItem( x );
-		return global.sessionStorage;
+		globalThis.sessionStorage.setItem( x, x );
+		globalThis.sessionStorage.removeItem( x );
+		return globalThis.sessionStorage;
 	} catch ( e ) {
 		return undefined;
 	}

src/test.js

@@ -1,5 +1,3 @@
-import global from "global";
-
 import { begin } from "./core";
 import { setTimeout, clearTimeout } from "./globals";
 import { emit } from "./events";
@@ -648,8 +646,8 @@ function saveGlobal() {
 	config.pollution = [];
 
 	if ( config.noglobals ) {
-		for ( const key in global ) {
-			if ( hasOwn.call( global, key ) ) {
+		for ( const key in globalThis ) {
+			if ( hasOwn.call( globalThis, key ) ) {
 
 				// In Opera sometimes DOM element ids show up here, ignore them
 				if ( /^qunit-test-output/.test( key ) ) {