[Robustness] use get-proto

Author: ljharb

index.js

@@ -4,7 +4,7 @@ var toStr = Object.prototype.toString;
 var fnToStr = Function.prototype.toString;
 var isFnRegex = /^\s*(?:function)?\*/;
 var hasToStringTag = require('has-tostringtag/shams')();
-var getProto = Object.getPrototypeOf;
+var getProto = require('get-proto');
 var getGeneratorFunc = function () { // eslint-disable-line consistent-return
 	if (!hasToStringTag) {
 		return false;

package.json

@@ -42,6 +42,7 @@
 		"url": "https://github.com/inspect-js/is-generator-function/issues"
 	},
 	"dependencies": {
+		"get-proto": "^1.0.0",
 		"has-tostringtag": "^1.0.2"
 	},
 	"devDependencies": {