update dev dependency react-dom for security fix

[taveras]

This change updates react-dom to version 16.2.1, per CVE-2018-6341.

Description

While this dependency is only used within our test suite and we would not be concerned about a XSS attack, we are upgrading react-dom regardless.

The following is information about the vulnerability:

React applications which rendered to HTML using the ReactDOMServer API were not escaping user-supplied attribute names at render-time. That lack of escaping could lead to a cross-site scripting vulnerability. This issue affected minor releases 16.0.x, 16.1.x, 16.2.x, 16.3.x, and 16.4.x. It was fixed in 16.0.1, 16.1.2, 16.2.1, 16.3.3, and 16.4.2.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore, documentation, cleanup

How Has This Been Tested?

Ran npm test, and verified the generated build with npm run build did not have issues.

Checklist:

• My code follows the code style of this project.
• I have updated the documentation (if required).
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[coveralls]

Pull Request Test Coverage Report for Build 271

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 263:	0.0%
Covered Lines:	60
Relevant Lines:	60

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💛 - Coveralls