Thanks for opening an issue for us!  Before you open an issue, please check if a similar issue exists or has been closed before.

If you're asking a question about how to use Blockly in your application, please ask questions on the [mailing list](https://groups.google.com/forum/#!forum/blockly) instead of filing issues.

_Please delete the above section and the instructions in the sections below before submitting.  If a section is not applicable, type "N/A" in that section._

### Problem statement

_Remove this hint: these checkboxes can be checked like this: [x]_

- [ ] Bug report
- [ ] Feature request

_What were you trying to do when you hit this bug?  Or, what do you want to do with Blockly that your proposed feature would enable?_

### Expected Behavior

_Please describe what should happen.  Include screenshots if applicable._

### Actual Behavior

_Describe what actually happens.  Include screenshots if applicable._

### Steps to Reproduce

_Explain what someone needs to do in order to see what's described in *Actual behavior* above_

### Stack Traces

```
Please open up the console.  If you see any Blockly-related errors, paste them here.

Ignore any instances of "Uncaught (in promise) DOMException: The play() request was interrupted by a call to pause()."
```

### Operating System and Browser

_Remove this hint: these checkboxes can be checked like this: [x]_

- [ ] Desktop:
  - [ ] Chrome
  - [ ] Firefox
  - [ ] Safari
  - [ ] Opera
  - [ ] IE 10+
  - [ ] IE 11
  - [ ] EDGE

- [ ] Smartphone/Tablet/Chromebook (please complete the following information):
  - Device: [e.g. iPhone6]
  - OS: [e.g. iOS8.1]
  - Browser [e.g. stock browser, safari]
  - Version [e.g. 22]

### Additional Information

_Anything else we should know?_