src/js.js: new globalThis compat routine

src/js.js

@@ -89,21 +89,25 @@ if (typeof process !== "undefined") {
 	} catch (e) {}
 }
 
-const global_env = (function() {
-	if (typeof process !== "undefined") {
-		/* node */
-		return global;
-	} else if (typeof window !== "undefined") {
-		/* browser window */
-		return window;
-	} else if (typeof WorkerGlobalScope !== 'undefined' && self instanceof WorkerGlobalScope) {
-		/* web worker */
-		return self;
-	} else {
-		/* unknown global env */
-		return (0, eval)('this'); /* use non-strict mode to get global env */
-	}
-})();
+const global_env = (function(Object) {
+	return typeof globalThis === 'object' ?
+		globalThis // eslint-disable-line no-undef
+		: (this ?
+			// compat: strict mode is unsupported
+			this
+			: ( // Based on https://mathiasbynens.be/notes/globalthis
+				Object.defineProperty(Object.prototype, '_', {
+					configurable: true,
+					get: function () {
+						delete Object.prototype._;
+						return this;
+					}
+				})
+				/* global _ */
+				, _
+			)
+		);
+}(Object));
 
 let apply, construct, Reflect_deleteProperty;
 if (typeof Reflect !== "undefined") {