Tiny optimisation to tree sorting

src/vs/workbench/parts/files/browser/views/explorerViewer.ts

@@ -569,10 +569,10 @@ export class FileSorter implements ISorter {
 	public compare(tree: ITree, statA: FileStat, statB: FileStat): number {
 
 		// Do not sort roots
-		if (statA.isRoot && statB.isRoot) {
+		if (statA.isRoot) {
+			if (statB.isRoot) {
 				return statA.rootIndex - statB.rootIndex;
 			}
-		if (statA.isRoot) {
 			return -1;
 		}
 		if (statB.isRoot) {