Remove dartc optimizing backend.

dart/compiler/java/com/google/dart/compiler/backend/common/AbstractBackend.java

Index: dart/compiler/java/com/google/dart/compiler/backend/common/AbstractBackend.java
diff --git a/dart/compiler/java/com/google/dart/compiler/backend/common/AbstractBackend.java b/dart/compiler/java/com/google/dart/compiler/backend/common/AbstractBackend.java
deleted file mode 100644
index 9779abab71a26167bc557d4f034c3b6add666294..0000000000000000000000000000000000000000
--- a/dart/compiler/java/com/google/dart/compiler/backend/common/AbstractBackend.java
+++ /dev/null
@@ -1,15 +0,0 @@
-// 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.backend.common;
-
-import com.google.dart.compiler.Backend;
-
-/**
- * Implementations of methods common to all the backends.
- *
- * @author johnlenz@google.com (John Lenz)
- */
-public abstract class AbstractBackend implements Backend {
-}