[Robustness] use call-bound

Author: ljharb

index.js

@@ -1,12 +1,14 @@
 'use strict';
 
-var toStr = Object.prototype.toString;
-var fnToStr = Function.prototype.toString;
+var callBound = require('call-bound');
 var safeRegexTest = require('safe-regex-test');
 var isFnRegex = safeRegexTest(/^\s*(?:function)?\*/);
 var hasToStringTag = require('has-tostringtag/shams')();
 var getProto = require('get-proto');
 
+var toStr = callBound('Object.prototype.toString');
+var fnToStr = callBound('Function.prototype.toString');
+
 var getGeneratorFunc = function () { // eslint-disable-line consistent-return
 	if (!hasToStringTag) {
 		return false;
@@ -22,11 +24,11 @@ module.exports = function isGeneratorFunction(fn) {
 	if (typeof fn !== 'function') {
 		return false;
 	}
-	if (isFnRegex(fnToStr.call(fn))) {
+	if (isFnRegex(fnToStr(fn))) {
 		return true;
 	}
 	if (!hasToStringTag) {
-		var str = toStr.call(fn);
+		var str = toStr(fn);
 		return str === '[object GeneratorFunction]';
 	}
 	if (!getProto) {

package.json

@@ -42,6 +42,7 @@
 		"url": "https://github.com/inspect-js/is-generator-function/issues"
 	},
 	"dependencies": {
+		"call-bound": "^1.0.3",
 		"get-proto": "^1.0.0",
 		"has-tostringtag": "^1.0.2",
 		"safe-regex-test": "^1.1.0"