Short-cut the function when all nodes are verified.

Author: Lifeng Lu

src/Microsoft.VisualStudio.Threading/JoinableTaskDependencyGraph.cs

@@ -772,6 +772,10 @@ private static void ComputeSelfAndDescendentOrJoinedJobsAndRemainTasks(IJoinable
                             foreach (KeyValuePair<IJoinableTaskDependent, int> item in dependencies)
                             {
                                 ComputeSelfAndDescendentOrJoinedJobsAndRemainTasks(item.Key, reachableNodes, remainNodes);
+                                if (remainNodes.Count == 0)
+                                {
+                                    return;
+                                }
                             }
                         }
                     }