Make incremental compilation opt-in.

dart/site/try/src/compilation.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library trydart.compilation;
 
 import 'dart:html' show
     Blob,
     Element,
     ErrorEvent,
@@ skipping 15 matching lines @@
     makeOutputFrame;
 
 import 'ui.dart' show
     buildButton,
     interaction,
     outputDiv,
     outputFrame;
 
 import 'settings.dart' show
     alwaysRunInWorker,
+    incrementalCompilation,
     minified,
     onlyAnalyze,
     verboseCompiler;
 
 import 'iframe_error_handler.dart' show
     errorStream;
 
 /**
  * Scheme for recognizing files stored in memory.
  *
@@ skipping 45 matching lines @@
 
   void start() {
     if (!shouldStartCompilation()) {
       receivePort.close();
       return;
     }
     if (current != null) current.dispose();
     current = this;
     var options = [
         '--analyze-main',
-        '--disable-type-inference',
-        '--incremental-support',
         '--no-source-maps',
     ];
     if (verboseCompiler) options.add('--verbose');
     if (minified) options.add('--minify');
     if (onlyAnalyze) options.add('--analyze-only');
+    if (incrementalCompilation.value) {
+      options.addAll(['--incremental-support', '--disable-type-inference']);
+    }
     interaction.compilationStarting();
     compilerPort.send([['options', options], receivePort.sendPort]);
     receivePort.listen(onMessage);
     compilerPort.send([source, receivePort.sendPort]);
   }
 
   void dispose() {
     if (worker != null) worker.terminate();
     objectUrls.forEach(Url.revokeObjectUrl);
   }
@@ skipping 132 matching lines @@
     if (seenMessages.add('$begin:$end: [$kind] $message')) {
       // Guard against duplicated messages.
       addDiagnostic(kind, message, begin, end);
     }
   }
 
   onCrash(data) {
     interaction.consolePrintLine(data);
   }
 }