Object.defineProperty is only missing in IE8.

src/Three.js

@@ -38,7 +38,7 @@ if ( Math.sign === undefined ) {
 
 }
 
-if ( Function.prototype.name === undefined && Object.defineProperty !== undefined ) {
+if ( Function.prototype.name === undefined ) {
 
 	// Missing in IE9-11.
 	// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/name