Fix for issue 3838, the exit on the -kill-after-perf now exits in an Eclipse workbench friendly man…

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUIStartup.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUIStartup.java
diff --git a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUIStartup.java b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUIStartup.java
index e13193f50b8b90334ee7e8d9aa2cbe6832fa29d7..d7a7f8692b0f3d5af304fc668b850b52b98e40d8 100644
--- a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUIStartup.java
+++ b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUIStartup.java
@@ -206,7 +206,13 @@ public class DartUIStartup implements IStartup {
               Performance.TIME_TO_INDEX_COMPLETE.log(DartEditorCommandLineManager.getStartTime());
               Performance.printResults_keyValue();
               if (DartEditorCommandLineManager.KILL_AFTER_PERF) {
-                System.exit(0);
+                // From the UI thread, call PlatformUI.getWorkbench().close() to exit the Dart Editor
+                Display.getDefault().syncExec(new Runnable() {
+                  @Override
+                  public void run() {
+                    PlatformUI.getWorkbench().close();
+                  }
+                });
               }
             }
           });