Wrap obj.constructor test in try/catch. Thanks to bkrausz. Fixes #9897

src/core.js

@@ -500,12 +500,17 @@ jQuery.extend({
 			return false;
 		}
 
+		try {
 			// Not own constructor property must be Object
 			if ( obj.constructor &&
 				!hasOwn.call(obj, "constructor") &&
 				!hasOwn.call(obj.constructor.prototype, "isPrototypeOf") ) {
 				return false;
 			}
+		} catch ( e ) {
+			// IE8,9 Will throw exceptions on certain host objects #9897
+			return false;
+		}
 
 		// Own properties are enumerated firstly, so to speed up,
 		// if last one is own, then all properties are own.

test/unit/core.js

@@ -290,7 +290,7 @@ test("type", function() {
 });
 
 test("isPlainObject", function() {
-	expect(14);
+	expect(15);
 
 	stop();
 
@@ -331,6 +331,13 @@ test("isPlainObject", function() {
 	// Window
 	ok(!jQuery.isPlainObject(window), "window");
 
+	try {
+		jQuery.isPlainObject( window.location );
+		ok( true, "Does not throw exceptions on host objects");
+	} catch ( e ) {
+		ok( false, "Does not throw exceptions on host objects -- FAIL");
+	}
+
 	try {
 		var iframe = document.createElement("iframe");
 		document.body.appendChild(iframe);