Refs #9057 : Fix test for property existence in property binding in the case...

Refs #9057 : Fix test for property existence in property binding in the case if property is a false boolean or a numeric equal to zero (#9064)

src/animation/PropertyBinding.js

@@ -163,7 +163,7 @@ THREE.PropertyBinding.prototype = {
 		// resolve property
 		var nodeProperty = targetObject[ propertyName ];
 
-		if ( ! nodeProperty ) {
+		if ( nodeProperty === undefined ) {
 
 			var nodeName = parsedPath.nodeName;