Fix tabsize setting (codesandbox#344)

Author: Ives van Hoorne

packages/app/src/app/pages/Sandbox/Editor/Content/index.js

@@ -27,7 +27,7 @@ const settings = store =>
     vimMode: store.preferences.settings.vimMode,
     lintEnabled: store.preferences.settings.lintEnabled,
     codeMirror: store.preferences.settings.codeMirror,
-    tabWidth: 2,
+    tabWidth: store.preferences.settings.tabSize || 2,
   }: Settings);
 
 type Props = {