Updates incremental compilation tests to work w/o code generation

compiler/javatests/com/google/dart/compiler/MockArtifactProvider.java

 // 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.
 
 package com.google.dart.compiler;
 
 import java.io.Reader;
 import java.io.StringReader;
 import java.io.StringWriter;
 import java.io.Writer;
@@ skipping 58 matching lines @@
       return null;
     }
 
     return artifact.writer.toString();
   }
 
   /**
    * Removes the given artifact, by name.
    */
   public void removeArtifact(String name, String part, String ext) {
-    artifacts.remove(keyFor(name, part, ext));
+   Artifact found = artifacts.remove(keyFor(name, part, ext));

[scheglov, 2012/02/25 21:47:18]

unused assignment

   }
 
   private String keyFor(Source source, String part, String ext) {
     return keyFor(source.getName(), part, ext);
   }
 
   private String keyFor(String sourceName, String part, String ext) {
     if (!part.isEmpty()) {
       part = "$" + part;
     }
     return sourceName + part + "/" + ext;
   }
 }