GLTFExporter: Clean up.

examples/js/exporters/GLTFExporter.js

@@ -1791,7 +1791,7 @@ THREE.GLTFExporter.prototype = {
 
 				}
 
-				if ( ! isIdentityMatrix( object.matrix ) ) {
+				if ( isIdentityMatrix( object.matrix ) === false ) {
 
 					gltfNode.matrix = object.matrix.elements;
 

examples/jsm/exporters/GLTFExporter.js

@@ -1811,7 +1811,7 @@ GLTFExporter.prototype = {
 
 				}
 
-				if ( ! isIdentityMatrix( object.matrix ) ) {
+				if ( isIdentityMatrix( object.matrix ) === false ) {
 
 					gltfNode.matrix = object.matrix.elements;