WebGLGeometries: Improve readability

src/renderers/webgl/WebGLGeometries.js

@@ -165,12 +165,12 @@ function WebGLGeometries( gl, attributes, info ) {
 
 	function getWireframeAttribute( geometry ) {
 
-		var geometryIndex = geometry.index;
-
 		var currentAttribute = wireframeAttributes[ geometry.id ];
 
 		if ( currentAttribute ) {
 
+			var geometryIndex = geometry.index;
+
 			if ( geometryIndex !== null ) {
 
 				// if the attribute is obsolete, create a new one