revert vscode cahnges (#4879)

src/vs/workbench/browser/parts/editor/editor.contribution.ts

@@ -123,7 +123,7 @@ class UntitledEditorInputFactory implements IEditorInputFactory {
 
 		// {{SQL CARBON EDIT}}
 		if (!untitledEditorInput.getResource()) {
-			return null;
+			return undefined;
 		}
 
 		let resource = untitledEditorInput.getResource();
@@ -927,4 +927,4 @@ MenuRegistry.appendMenuItem(MenuId.MenubarGoMenu, {
 	title: nls.localize({ key: 'miSwitchGroup', comment: ['&& denotes a mnemonic'] }, "Switch &&Group"),
 	submenu: MenuId.MenubarSwitchGroupMenu,
 	order: 2
-});
+});