Tests only: implement new method

compiler/tests-common/org/jetbrains/kotlin/test/testFramework/mock/MockPsiDocumentManager.java

@@ -139,6 +139,11 @@ public class MockPsiDocumentManager extends PsiDocumentManager {
     throw new UnsupportedOperationException();
   }
 
+  @Override
+  public void performLaterWhenAllCommitted(@NotNull Runnable runnable) {
+    throw new UnsupportedOperationException();
+  }
+
   @Override
   public void reparseFiles(@NotNull Collection<VirtualFile> files, boolean includeOpenFiles) {
     throw new UnsupportedOperationException();