Doing some cleanup.

src/site/js/Switcher.dart

-// XXX: This file isn't used right now
-
-import 'dart:html';
-
-final List<String> osList = const <String>['macos', 'windows', 'linux'];  // all supported OSs
-String osName = 'linux'; // the currently displayed platform
-
-/** Initializes osName and selects the corresponding radio button. */
-void detectPlatform() {
-  // osName is initially 'linux', since linux strings are unpredictable.
-  if (window.navigator.appVersion.contains('Win')) {
-    osName = 'windows';
-  } else if (window.navigator.appVersion.contains('Mac')) {
-    osName = 'macos';
-  }
-  document.querySelector('#$osName').attributes['checked'] = 'true';
-}
-
-/** Shows the text for the chosen platform (and no other). */
-void filterPlatformText() {
-  // Get all the platform-specific elements.
-  osList.forEach((os) {
-    bool shouldShow = (os == osName);
-    document.querySelectorAll('.$os').forEach((el) {
-      el.hidden = !shouldShow; // Show or hide each element.
-    });
-  });
-}
-
-/** Allows the user to choose the OS. */
-void registerHandlers() {
-  osList.forEach((os) {
-    document.querySelector('#$os').onClick.listen((e) {
-      osName = os;
-      filterPlatformText();
-    });
-  });
-}
-
-/** Ready, set, go! */
-void main() {
-  detectPlatform();
-  filterPlatformText();
-  registerHandlers();
-}