build(deps): bump core-js from 2.5.7 to 2.6.0

[dependabot-preview]

Bumps core-js from 2.5.7 to 2.6.0.

Release notes

Sourced from core-js's releases.

2.6.0 - 2018.12.05

• Add direct .exec calling to RegExp#{@[**replace**](https://github.com/replace), @[**split**](https://github.com/split), @[**match**](https://github.com/match), @[**search**](https://github.com/search)}. Also, added fixes for RegExp#exec method. #411, #428, #434, #435, #453, #458, thanks [nicolo-ribaudo](https://github.com/nicolo-ribaudo).

Changelog

Sourced from core-js's changelog.

2.6.0 - 2018.12.05

• Add direct .exec calling to RegExp#{@[**replace**](https://github.com/replace), @[**split**](https://github.com/split), @[**match**](https://github.com/match), @[**search**](https://github.com/search)}. Also, added fixes for RegExp#exec method. #428, #435, #458, thanks [nicolo-ribaudo](https://github.com/nicolo-ribaudo).

Commits

• f980318 2.6.0
• f0b4154 add es6.regexp.exec as a direct dependency of _fix-re-wks for prevent bre...
• a221e2a replace redefine by hide because of Chrome 38 bug with symbols conversion
• 41e41e9 add some caps for the library version
• 79db861 Merge pull request #458 from nicolo-ribaudo/backport-453
• b0a70f9 Backport 41a8b12c8e641061e3576f89023f0a8fa903b81b
• f77f88e Backport gh-453
• 04b76e8 Merge pull request #435 from nicolo-ribaudo/backport-named-replace
• 2b102b7 Polyfll named groups in RegExp#@replace
• fd64c48 Merge pull request #428 from nicolo-ribaudo/backport-es2015-regex
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge
• @dependabot reopen will reopen this PR if it is closed
• @dependabot ignore this [patch|minor|major] version will close this PR and stop Dependabot creating any more for this minor/major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
• @dependabot use these labels will set the current labels as the default for future PRs for this repo and language
• @dependabot use these reviewers will set the current reviewers as the default for future PRs for this repo and language
• @dependabot use these assignees will set the current assignees as the default for future PRs for this repo and language
• @dependabot use this milestone will set the current milestone as the default for future PRs for this repo and language
• @dependabot badge me will comment on this PR with code to add a "Dependabot enabled" badge to your readme

Additionally, you can set the following in your Dependabot dashboard:

• Update frequency (including time of day and day of week)
• Automerge options (never/patch/minor, and dev/runtime dependencies)
• Pull request limits (per update run and/or open at any time)
• Out-of-range updates (receive only lockfile updates, if desired)
• Security updates (receive only security updates, if desired)

Finally, you can contact us by mentioning @dependabot.