Update systemjs-builder to version 0.15.15 🚀

[greenkeeperio-bot]

Hello :wave:

:rocket::rocket::rocket:

systemjs-builder just published its new version 0.15.15, which is not covered by your current version range.

If this pull request passes your tests you can publish your software with the latest version of systemjs-builder – otherwise use this branch to work on adaptions and fixes.

Happy fixing and merging :palm_tree:

---

The new version differs by 443 commits .

• fd02cf4 0.15.15
• ea936ba allow null globals
• 35d55b5 ensure modules list correctly returned for full-tree rollup
• d126587 revert b7084ccc58, leave the global require intact
• 5c5b744 amd adjustment for object destructuring
• 6f25cda conditional fallback does not go through package map
• 6416371 ensure returned output.modules is ordered
• 8bac50b proper circular conditional error, fix #1599 again
• b874bdf 0.15.14
• f8abda4 fix conditional tracing deps
• e7b4ca5 fixes jspm/jspm-cli#1660, add static tree info
• b7084cc ensure global require is cleared on executions
• b5cf432 Merge pull request #535 from arackaf/parentheses-support-in-bundle-arithmetic
• eba62fe throw on no package map
• bb312f7 invalidate to use decanonicalize

There are 250 commits in total. See the full diff.

---

This pull request was created by greenkeeper.io. It keeps your software, up to date, all the time.

_{Tired of seeing this sponsor message? Upgrade to the supporter plan! You'll also get your pull requests faster :zap:}