Update PR #4383 with various fixes

[BenHenning]

Explanation

This issue is aiding in the investigation and fixing of oppia#4383.

The main issue I ran into was a build failure that seems to have come up from syncing with the latest develop changes.

I ran all of the Mark*CompletedTest suites 20 times each and did not see any flaky results (every run passed as expected).

Essential Checklist

• The PR title and explanation each start with "Fix #bugnum: " (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• Any changes to scripts/assets files have their rationale included in the PR explanation.
• The PR follows the style guide.
• The PR does not contain any unnecessary code changes from Android Studio (reference).
• The PR is made from a branch that's not called "develop" and is up-to-date with "develop".
• The PR is assigned to the appropriate reviewers (reference).

For UI-specific PRs only

N/A -- This just fixes a build error & doesn't change existing UIs or tests.

[BenHenning]

@KevinGitonga PTAL.