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/MockFile.java

Index: editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockFile.java
diff --git a/editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockFile.java b/editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockFile.java
index 05ceac9b6e8648e79b7e515c66041fec93b97d1d..63576c745718470e373407f0a189137bfb4bfb44 100644
--- a/editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockFile.java
+++ b/editor/tools/plugins/com.google.dart.tools.core_test/src/com/google/dart/tools/core/mock/MockFile.java
@@ -13,6 +13,9 @@
  */
 package com.google.dart.tools.core.mock;
 
+import com.google.dart.engine.internal.context.TimestampedData;
+import com.google.dart.engine.source.FileBasedSource;
+import com.google.dart.engine.source.Source;
 import com.google.dart.tools.core.CallList.Call;
 import com.google.dart.tools.core.DartCore;
 
@@ -92,6 +95,32 @@ public class MockFile extends MockResource implements IFile {
     getMarkerCallList().assertNoCall(newDeleteMarkerCall());
   }
 
+  /**
+   * Answer a source representing this file
+   * 
+   * @return a source, not {@code null}
+   */
+  public Source asSource() {
+    return new FileBasedSource(toFile()) {
+      @Override
+      public boolean equals(Object object) {
+        return object instanceof Source && getFullName().equals(((Source) object).getFullName());
+      }
+
+      @Override
+      public boolean exists() {
+        return MockFile.this.exists();
+      }
+
+      @Override
+      public TimestampedData<CharSequence> getContents() throws Exception {
+        return new TimestampedData<CharSequence>(
+            getModificationStamp(),
+            MockFile.this.getContentsAsString());
+      }
+    };
+  }
+
   @Override
   public void create(InputStream source, boolean force, IProgressMonitor monitor)
       throws CoreException {