Fix infinite loop because of props mutation

src/create-element.js

@@ -1,4 +1,5 @@
 import options from './options';
+import { assign } from './util';
 
 /**
   * Create an virtual node (used for JSX)
@@ -9,7 +10,8 @@ import options from './options';
   * @returns {import('./internal').VNode}
   */
 export function createElement(type, props, children) {
-	if (props==null) props = {};
+	props = assign({}, props);
+
 	if (arguments.length>3) {
 		children = [children];
 		for (let i=3; i<arguments.length; i++) {

test/browser/render.test.js

@@ -4,6 +4,7 @@ import { setupRerender } from 'preact/test-utils';
 import { createElement as h, render, Component } from '../../src/index';
 import { setupScratch, teardown, getMixedArray, mixedArrayHTML, sortCss, serializeHtml, supportsPassiveEvents, supportsDataList } from '../_util/helpers';
 import { clearLog, getLog, logCall } from '../_util/logCall';
+import options from '../../src/options';
 
 /** @jsx h */
 
@@ -975,6 +976,29 @@ describe('render()', () => {
 		expect(scratch.textContent).to.equal('01');
 	});
 
+	it('should not cause infinite loop with referentially equal props', () => {
+		let i = 0;
+		let prevDiff = options.diff;
+		options.diff = () => {
+			if (++i > 10) {
+				options.diff = prevDiff;
+				throw new Error('Infinite loop');
+			}
+		};
+
+		function App({ children, ...rest }) {
+			return (
+				<div {...rest}>
+					<div {...rest}>{children}</div>
+				</div>
+			);
+		}
+
+		render(<App>10</App>, scratch);
+		expect(scratch.textContent).to.equal('10');
+		options.diff = prevDiff;
+	});
+
 	describe('replaceNode parameter', () => {
 
 		function appendChildToScratch(id) {

test/shared/createContext.test.js

@@ -23,7 +23,7 @@ describe('createContext', () => {
 
 		const providerComponent = <Provider {...contextValue}>{children}</Provider>;
 		//expect(providerComponent).to.have.property('tag', 'Provider');
-		expect(providerComponent).to.have.property('props', contextValue);
-		expect(providerComponent).with.nested.deep.property('props.children', children);
+		expect(providerComponent.props.value).to.equal(contextValue.value);
+		expect(providerComponent.props.children).to.equal(children);
 	});
 });

test/shared/createElement.test.js

@@ -39,7 +39,7 @@ describe('createElement(jsx)', () => {
 
 	it('should set VNode#props property', () => {
 		const props = {};
-		expect(h('div', props)).to.have.property('props', props);
+		expect(h('div', props).props).to.deep.equal(props);
 	});
 
 	it('should set VNode#text property', () => {