Bump babel-plugin-istanbul from 5.1.1 to 5.1.4 (#2012)
Bump babel-plugin-istanbul from 5.1.1 to 5.1.4 (#2012)

Bumps [babel-plugin-istanbul](https://github.com/istanbuljs/babel-plugin-istanbul) from 5.1.1 to 5.1.4.
- [Release notes](https://github.com/istanbuljs/babel-plugin-istanbul/releases)
- [Changelog](https://github.com/istanbuljs/babel-plugin-istanbul/blob/master/CHANGELOG.md)
- [Commits](https://github.com/istanbuljs/babel-plugin-istanbul/compare/v5.1.1...v5.1.4)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
Khan/KaTeX,xymostech/KaTeX,xymostech/KaTeX,xymostech/KaTeX,Khan/KaTeX,xymostech/KaTeX,xymostech/KaTeX,Khan/KaTeX