dispose fixture root disposable before project fixture tearDown

the latter checks if temp injectors are removed, and they're removed in the former
should fix damn flaky PsiAnchorTest (still not sure why flaky)

platform/testFramework/src/com/intellij/testFramework/fixtures/impl/BaseFixture.java

@@ -47,11 +47,19 @@ public class BaseFixture implements IdeaTestFixture {
   public void tearDown() throws Exception {
     Assert.assertTrue("setUp() has not been called", myInitialized);
     Assert.assertFalse("tearDown() already has been called", myDisposed);
-    EdtTestUtil.runInEdtAndWait(() -> Disposer.dispose(myTestRootDisposable));
+    disposeRootDisposable();
     myDisposed = true;
     resetClassFields(getClass());
   }
 
+  protected void disposeRootDisposable() {
+    EdtTestUtil.runInEdtAndWait(() -> {
+      if (!Disposer.isDisposed(myTestRootDisposable)) {
+        Disposer.dispose(myTestRootDisposable);
+      }
+    });
+  }
+
   private void resetClassFields(final Class<?> aClass) {
     try {
       UsefulTestCase.clearDeclaredFields(this, aClass);

platform/testFramework/src/com/intellij/testFramework/fixtures/impl/CodeInsightTestFixtureImpl.java

@@ -1237,6 +1237,7 @@ public class CodeInsightTestFixtureImpl extends BaseFixture implements CodeInsig
         myChooseByNamePopup = null;
       })
       // don't use method references here to make stack trace reading easier 
+      .append(() -> disposeRootDisposable()) 
       .append(() -> EdtTestUtil.runInEdtAndWait(() -> myProjectFixture.tearDown())) 
       .append(() -> EdtTestUtil.runInEdtAndWait(() -> myTempDirFixture.tearDown()))
       .append(() -> super.tearDown())