We purge it [here](https://github.com/facebook/react/blob/b11540ccb2321aeb7259fcf0b3a38aeeea35231d/src/isomorphic/ReactDebugTool.js#L88-L89) but this code doesn’t run because of the [early exit](https://github.com/facebook/react/blob/b11540ccb2321aeb7259fcf0b3a38aeeea35231d/src/isomorphic/ReactDebugTool.js#L53-L57).

Need to fix this and add a test case to make sure we don’t regress on it.

warning(debugID, 'ReactDebugTool: debugID may not be empty.');
}
var ReactDebugTool = {
  addDevtool(devtool) {
    eventHandlers.push(devtool);
  },
  removeDevtool(devtool) {
    for (var i = 0; i < eventHandlers.length; i++) {
      if (eventHandlers[i] === devtool) {
        eventHandlers.splice(i, 1);
        i--;
      }
    }
  },
  beginProfiling() {
    if (__DEV__) {
      if (isProfiling) {
        return;
      }
      isProfiling = true;
      flushHistory.length = 0;
      resetMeasurements();
    }
  },
  endProfiling() {