Integrate leg as a component in test.py. Also update presubmit script to run tests with leg.

dart/frog/leg/compiler.dart

 // Copyright (c) 2011, 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.
 
 class Compiler implements Canceler, Logger {
   final Script script;
   Queue<SourceString> worklist;
   Universe universe;
 
   List<CompilerTask> tasks;
@@ skipping 32 matching lines @@
     } catch (CompilerCancelledException exception) {
       log(exception.toString());
       log('compilation failed');
       return false;
     }
     // TODO(floitsch): the following code can be removed once the HTracer
     // writes directly into a file.
     if (GENERATE_SSA_TRACE) {
       print("------------------");
       print(new HTracer.singleton());
-      print("------------------");      
+      print("------------------");
     }
     log('compilation succeeded');
     return true;
   }
 
   void runCompiler() {
     scanner.scan(script);
     while (!worklist.isEmpty()) {
       SourceString name = worklist.removeLast();
       Element element = universe.find(name);
@@ skipping 56 matching lines @@
 var print = (typeof console == 'object')
     ? function(obj) { console.log(obj); }
     : function(obj) { write(obj); write('\\n'); };
 """;
 
 final String ADD_SUPPORT = """
 function \$add(a, b) {
   return a + b;
 }
 """;