remove files from index when do-not-analyze is selected

editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockContainer.java

Index: editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockContainer.java
diff --git a/editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockContainer.java b/editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockContainer.java
index 553c6f8ad80d03d065431c3b9719d77e2e0301ad..e5f5ef037f40d26cb071e4b8018f37dc11c98d18 100644
--- a/editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockContainer.java
+++ b/editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockContainer.java
@@ -13,6 +13,9 @@
  */
 package com.google.dart.tools.core.mock;
 
+import com.google.dart.engine.source.DirectoryBasedSourceContainer;
+import com.google.dart.engine.source.SourceContainer;
+
 import static com.google.dart.tools.core.DartCore.isDartLikeFileName;
 import static com.google.dart.tools.core.DartCore.isHtmlLikeFileName;
 
@@ -109,6 +112,15 @@ public abstract class MockContainer extends MockResource implements IContainer {
     return folder;
   }
 
+  /**
+   * Answer a source container representing this container
+   * 
+   * @return a container, not {@code null}
+   */
+  public SourceContainer asSourceContainer() {
+    return new DirectoryBasedSourceContainer(toFile());
+  }
+
   @Override
   public IResourceFilterDescription createFilter(int type,
       FileInfoMatcherDescription matcherDescription, int updateFlags, IProgressMonitor monitor)