Trying to solve the root cause:
`Editor.maybeEmitChange` calls `this.eventHub.emit('editorChange')`, and
then `Compiler.onEditorChange` calls `this.compile()` .
So the idiom
```ts
this.maybeEmitChange();
this.requestCompilation();
```
repeated a few times in editor.ts, causes two rapid (and redundant)
invocations of `compile`, which in turn cause the race. This PR removes
all calls to `Editor.requestCompilation` and in fact removes the
function entirely.
I'm guessing `maybeEmitChange` is a late addition to solve some other
problems, and this race was an unintended side effect, but please
correct me if you have better understanding of the code and its history.
52b5a2042d