### Describe what you were doing when the bug occurred:
1. I did profiling on a list, that gets updated on each pagination api call.
2. Once the profiling was done, I moved around in the Profiler to view the Flamegraph
3. Moving to second capture, the Profiler crashed.


**DevTools version**: 4.6.0-6cceaeb67

```
Component stack: in ec
    in div
    in div
    in div
    in So
    in Unknown
    in n
    in Unknown
    in div
    in div
    in rl
    in Ze
    in fn
    in Ga
    in _s
```
The
       chi
       to 
      for (let j = 0; j < pendingSimulatedUnmountedIDs.length; j++) {
        operations[i + j] = pendingSimulatedUnmountedIDs[j];
      }
      i += pendingSimulatedUnmountedIDs.length;
       The 
      if (pendingUnmountedRootID !== null) {
        operations[i] = pendingUnmountedRootID;
        i++;
      }
    }
     Fill in the rest of the operations.
    for (let j = 0; j < pendingOperations.length; j++) {
      operations[i + j] = pendingOperations[j];
    }
    i += pendingOperations.length;
     Let the frontend know about tree operations.
    flushOrQueueOperations(operations);
     Reset all of the pending state now that we've told the frontend about it.
    pendingOperations.length = 0;
    pendingRealUnmountedIDs.length = 0;
    pendingSimulatedUnmountedIDs.length = 0;
    pendingUnmountedRootID = null;
    pendingStringTable.clear();
    pendingStringTableLength = 0;
  }
  function getStringID(str: string | null): number {
    if (str === null) {