Lots of frog cleanup

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.
@@ skipping 388 matching lines @@
     }
     return res;
   }
 
   void runCompilationPhases() {
     final lib = withTiming('first pass', () => processDartScript());
     withTiming('resolve top level', resolveAll);
     if (experimentalAwaitPhase != null) {
       withTiming('await translation', experimentalAwaitPhase);
     }
+    withTiming('analyze pass', () { analyzeCode(lib); });
     withTiming('generate code', () { generateCode(lib); });
   }
 
   String getGeneratedCode() {
     // TODO(jimhug): Assert compilation is all done here.
     if (legCode != null) {
       assert(options.enableLeg);
       return legCode;
     } else {
       return frogCode;
@@ skipping 58 matching lines @@
   }
 
   findMainMethod(Library lib) {
     var main = lib.lookup('main', lib.span);
     if (main == null) {
       fatal('no main method specified');
     }
     return main;
   }
 
+  /**
+   * Walks all code in lib and imports for analysis.
+   */
+  analyzeCode(Library lib) {
+    gen = new WorldGenerator(findMainMethod(lib), new CodeWriter());
+    gen.analyze();
+  }
+
+  /**
+   * Walks all live code to generate JS source for output.
+   */
   generateCode(Library lib) {
-    gen = new WorldGenerator(findMainMethod(lib), new CodeWriter());
     gen.run();
     frogCode = gen.writer.text;
     jsBytesWritten = frogCode.length;
     gen = null;
   }
 
   // ********************** Message support ***********************
 
   void _message(String color, String prefix, String message,
       SourceSpan span, SourceSpan span1, SourceSpan span2, bool throwing) {
@@ skipping 107 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;
   }
 }