Add unitAboutToCompile() into DartCompilerListener

compiler/javatests/com/google/dart/corelib/SharedTestCase.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.corelib;
 
 import com.google.dart.compiler.CommandLineOptions.CompilerOptions;
-import com.google.dart.compiler.ast.DartUnit;
 import com.google.dart.compiler.CompilerConfiguration;
 import com.google.dart.compiler.DartArtifactProvider;
 import com.google.dart.compiler.DartCompilationError;
 import com.google.dart.compiler.DartCompiler;
 import com.google.dart.compiler.DartCompilerListener;
 import com.google.dart.compiler.DefaultCompilerConfiguration;
 import com.google.dart.compiler.DefaultDartArtifactProvider;
 import com.google.dart.compiler.DefaultLibrarySource;
 import com.google.dart.compiler.ErrorSeverity;
 import com.google.dart.compiler.LibrarySource;
@@ skipping 192 matching lines @@
         CharArrayWriter writer = artifacts.get(uri);
         if (writer != null) {
           return new CharArrayReader(writer.toCharArray());
         }
         return provider.getArtifactReader(source, part, extension);
       }
     };
   }
 
   private DartCompilerListener getListener() {
-    DartCompilerListener listener = new DartCompilerListener() {
+    DartCompilerListener listener = new DartCompilerListener.Empty() {
       @Override
       public void onError(DartCompilationError event) {
         if (event.getErrorCode().getSubSystem() == SubSystem.STATIC_TYPE) {
           typeErrorCount.incrementAndGet();
         } else if (event.getErrorCode().getErrorSeverity() == ErrorSeverity.ERROR) {
           compilationErrorCount.incrementAndGet();
         } else if (event.getErrorCode().getErrorSeverity() == ErrorSeverity.WARNING) {
           warningCount.incrementAndGet();
         }
         maybeThrow(event);
       }
 
       private void maybeThrow(DartCompilationError event) {
         if (isNegative) {
           return;
         }
         if (outcomes.contains("pass")) {
           // It is easier to debug a failing regular test if we throw an exception.
           throw new AssertionError(event);
         }
       }
-
-      @Override
-      public void unitCompiled(DartUnit unit) {
-      }
     };
     return listener;
   }
 
   private void analyzeNormalCompletion() {
     if (isNegative) {
       if (!outcomes.contains("fail")) {
         fail("Negative test didn't cause an error");
       }
     } else {
@@ skipping 29 matching lines @@
     String[] fields = SEPARATOR.split(line);
     assertTrue(line, fields.length > 3);
     String name = fields[0];
     Set<String> outcomes = new HashSet<String>(Arrays.<String>asList(fields[1].split(",")));
     boolean isNegative = fields[2].equals("True");
     String[] arguments = new String[fields.length - 3];
     System.arraycopy(fields, 3, arguments, 0, arguments.length);
     return new SharedTestCase(name, outcomes, isNegative, regularCompile, arguments) {};
   }
 }