Added support for dumping AST to console, text file or dot file

compiler/java/com/google/dart/compiler/ast/viz/TextWriter.java

Index: compiler/java/com/google/dart/compiler/ast/viz/TextWriter.java
===================================================================
--- compiler/java/com/google/dart/compiler/ast/viz/TextWriter.java	(revision 0)
+++ compiler/java/com/google/dart/compiler/ast/viz/TextWriter.java	(revision 0)
@@ -0,0 +1,39 @@
+// 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.ast.viz;
+
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+
+import com.google.dart.compiler.ast.DartUnit;
+
+/**
+ * Write the AST in Text format. Output file is placed
+ * next to the JS file in the output directory
+ */
+public class TextWriter extends ConsoleWriter {
+  
+  public TextWriter(String outputDir) {
+    super(outputDir);
+  }
+    
+  @Override
+  public Object visitUnit(DartUnit node) {
+    if(!isIgnored(node)){
+      String txtFilePath = outputDir + File.separator 
+          + currentUnit.getSource().getUri() + ".ast.txt";
+      makeParentDirs(txtFilePath);
+      try {
+        //Set output to text file
+        out = new FileWriter(new File(txtFilePath));
+      } catch (IOException e) {
+        e.printStackTrace();
+      }
+      visitChildren(node);
+    }
+    return null;
+  }
+}