Ground work for addition to new listener api

compiler/javatests/com/google/dart/corelib/SharedTestCase.java

Index: compiler/javatests/com/google/dart/corelib/SharedTestCase.java
diff --git a/compiler/javatests/com/google/dart/corelib/SharedTestCase.java b/compiler/javatests/com/google/dart/corelib/SharedTestCase.java
index ca534f9db8c67b6dc3b8d5a9edcd03d09d50ecde..ee74c8f4346e1a1cc6fb50b6472c14064b43535a 100644
--- a/compiler/javatests/com/google/dart/corelib/SharedTestCase.java
+++ b/compiler/javatests/com/google/dart/corelib/SharedTestCase.java
@@ -5,6 +5,7 @@
 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;
@@ -243,6 +244,10 @@ public class SharedTestCase extends TestCase {
         typeErrorCount.incrementAndGet();
         maybeThrow(event);
       }
+
+      @Override
+      public void unitCompiled(DartUnit unit) {
+      }
     };
     return listener;
   }