Add secret option "live" which compiles more frequently.

dart/site/try/src/settings.dart

Index: dart/site/try/src/settings.dart
diff --git a/dart/site/try/src/settings.dart b/dart/site/try/src/settings.dart
index 904f2afef68928f0e730d72c82b365945769d3a3..9778206a953e3cf77f78d89fd39e121b01cf61f5 100644
--- a/dart/site/try/src/settings.dart
+++ b/dart/site/try/src/settings.dart
@@ -93,6 +93,8 @@ const BooleanUserOption enableCodeCompletion =
 const BooleanUserOption incrementalCompilation =
     const BooleanUserOption('incrementalCompilation');
 
+const BooleanUserOption live = const BooleanUserOption('live', isHidden: true);
+
 const List<UserOption> options = const <UserOption>[
     _alwaysRunInWorker,
     _verboseCompiler,
@@ -101,8 +103,9 @@ const List<UserOption> options = const <UserOption>[
     _enableDartMind,
     _compilationPaused,
     incrementalCompilation,
+    live,
+    enableCodeCompletion,
     _codeFont,
     _theme,
     _currentSample,
-    enableCodeCompletion,
   ];