Remove frog dependencies from lib/compiler.

frog/world.dart

 // Copyright (c) 2012, 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.
 
 /** The one true [World]. */
 World world;
 
 /**
  * Experimental phase to enable await, only set when using the
  * await/awaitc.dart entrypoint.
  */
 Function experimentalAwaitPhase;
 
 /**
  * Set when the leg compiler is available.  Should always be set
- * to leg/frog_leg.dart/compile.
+ * to frog_leg/compile.
  */
 typedef bool LegCompile(World world);
 LegCompile legCompile;
 
 typedef void MessageHandler(String prefix, String message, SourceSpan span);
 
 
 /**
  * Should be called exactly once to setup singleton world.
  * Can use world.reset() to reinitialize.
@@ skipping 690 matching lines @@
 
   withTiming(String name, f()) {
     final sw = new Stopwatch();
     sw.start();
     var result = f();
     sw.stop();
     info('$name in ${sw.elapsedInMs()}msec');
     return result;
   }
 }