Fix issue where xhr.upload is undefined on Android

[ryanlntn]

When attempting to set xhr.upload.onprogress on Android I get the following error:
undefined is not an object (evaluating 'xhr.upload')

Looking at the iOS implementation of XMLHTTPRequest I found the following code:

  constructor() {
    super();
    // iOS supports upload
    this.upload = {};
  }

Applying the same constructor to the Android implementation resolves the issue.

[facebook-github-bot]

By analyzing the blame information on this pull request, we identified @mkonicek, @klvs and @lexs to be potential reviewers.

[dsibiski]

@ryanlntn Thanks for the PR! I was looking at XMLHttpRequestBase.js to see if we could consolidate the duplicate code into this base component and I saw this:

constructor() {
    ...
    this.upload = undefined; /* Upload not supported yet */
    ...
}

XMLHttpRequestBase.js#L92

I wonder what the comment means? Is that still true? It appears to be working with the fix here...

@nicklockwood @mkonicek @lexs @philikon any thoughts?

[philikon]

Yeah, I don't see any reason why we can't at least expose the upload object on Android. It doesn't say anywhere that we have to support all events on it.

I actually have a work-in-progress to make XHR a proper EventTarget: philikon@5bb05bb

[philikon]

Ok, I cleaned up my patched and submitted it as a PR: #7017.

[ghost]

@philikon would you mind taking a look at this pull request? It's been a while since the last commit was reviewed.

[philikon]

We can close this PR, it's been superseded by #7017.