fix(full): ensure prototype methods are copied;

- Closes #24

src/full.js

@@ -11,7 +11,7 @@ export function klona(x) {
 	var i=0, k, list, tmp, str=Object.prototype.toString.call(x);
 
 	if (str === '[object Object]') {
-		tmp = typeof x.constructor === 'function' ? new x.constructor() : Object.create(null);
+		tmp = Object.create(x.__proto__ || null);
 	} else if (str === '[object Array]') {
 		tmp = Array(x.length);
 	} else if (str === '[object Set]') {
@@ -39,7 +39,7 @@ export function klona(x) {
 	}
 
 	if (tmp) {
-		for (list = Object.getOwnPropertySymbols(x); i < list.length; i++) {
+		for (list=Object.getOwnPropertySymbols(x); i < list.length; i++) {
 			set(tmp, list[i], Object.getOwnPropertyDescriptor(x, list[i]));
 		}
 

test/suites/class.js

@@ -34,6 +34,65 @@ export default function (klona) {
 		assert.equal(output.val, 42);
 	});
 
+	Classes('prototype methods :: manual', () => {
+		function Test() {}
+
+		Test.prototype = {
+			count: 0,
+			increment() {
+				this.count++;
+			}
+		};
+
+		const input = new Test();
+		const output = klona(input);
+
+		assert.equal(input.count, 0);
+		assert.equal(output.count, 0);
+
+		assert.equal(typeof input.increment, 'function');
+		assert.equal(typeof output.increment, 'function');
+
+		output.increment();
+		assert.equal(input.count, 0);
+		assert.equal(output.count, 1);
+
+		input.increment();
+		assert.equal(input.count, 1);
+		assert.equal(output.count, 1);
+	});
+
+	Classes('prototype methods :: class', () => {
+		class Test {
+			constructor() {
+				this.count = 0;
+			}
+			increment() {
+				this.count++
+			}
+		}
+
+		const input = new Test();
+		const output = klona(input);
+
+		assert.deepEqual(input, output);
+		assert.deepEqual(output.__proto__, Test.prototype);
+
+		assert.equal(input.count, 0);
+		assert.equal(output.count, 0);
+
+		assert.equal(typeof input.increment, 'function');
+		assert.equal(typeof output.increment, 'function');
+
+		output.increment();
+		assert.equal(input.count, 0);
+		assert.equal(output.count, 1);
+
+		input.increment();
+		assert.equal(input.count, 1);
+		assert.equal(output.count, 1);
+	});
+
 	Classes('constructor properties', () => {
 		function Test (num) {
 			this.value = num;