Change our editor tab spacing defaults to 2 spaces.

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/text/DartSourceViewerConfiguration.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/text/DartSourceViewerConfiguration.java
===================================================================
--- editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/text/DartSourceViewerConfiguration.java	(revision 1624)
+++ editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/text/DartSourceViewerConfiguration.java	(working copy)
@@ -1,11 +1,11 @@
 /*
  * Copyright (c) 2011, the Dart project authors.
- *
+ * 
  * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
- *
+ * 
  * http://www.eclipse.org/legal/epl-v10.html
- *
+ * 
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
  * or implied. See the License for the specific language governing permissions and limitations under
@@ -104,6 +104,8 @@
 @SuppressWarnings("restriction")
 public class DartSourceViewerConfiguration extends TextSourceViewerConfiguration {
 
+  private static final int TAB_WIDTH_IN_SPACES = 2;
+
   /**
    * Creates and returns a preference store which combines the preference stores from the text tools
    * and which is read-only.
@@ -632,7 +634,7 @@
    */
   @Override
   public int getTabWidth(ISourceViewer sourceViewer) {
-    return super.getTabWidth(sourceViewer);
+    return TAB_WIDTH_IN_SPACES;
     // return CodeFormatterUtil.getTabWidth(getProject());
   }