Update dependency babel-core to v6.26.3

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
babel-core (source)	6.26.0 -> 6.26.3

---

Release Notes

babel/babel

v6.26.3

Compare Source

Summary

• Fixed a small regression from the backport of #​7761 from #​7812 if the output file contains no JS content

v6.26.2

Compare Source

Summary

• Landed #​7812 which backported several fixes to make sourcemaps behave better
  • #​7312 - Include better mappings for arrow-transformed 'this' and 'arguments'
  • #​7378 - Include better mappings for import bindings transformed to member expressions
  • #​7761 - Re-implement inputSourceMap merging logic to more accurately reflect mappings

---

Renovate configuration

📅 Schedule: At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻️ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR has been generated by WhiteSource Renovate. View repository job log here.