Update acorn to version 4.0.1 🚀

[greenkeeperio-bot]

Hello lovely humans,

acorn just published its new version 4.0.1.

State	Update 🚀
Dependency	acorn
New version	4.0.1
Type	dependency

This version is not covered by your current version range.

Without accepting this pull request your project will work just like it did before. There might be a bunch of new features, fixes and perf improvements that the maintainers worked on for you though.

I recommend you look into these changes and try to get onto the latest version of acorn.
Given that you have a decent test suite, a passing build is a strong indicator that you can take advantage of these changes by merging the proposed change into your project. Otherwise this branch is a great starting point for you to work on the update.

Do you have any ideas how I could improve these pull requests? Did I report anything you think isn’t right?
Are you unsure about how things are supposed to work?

There is a collection of frequently asked questions and while I’m just a bot, there is a group of people who are happy to teach me new things. Let them know.

Good luck with your project ✨

You rock!

🌴

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The new version differs by 81 commits .

• cb95800 Mark release 4.0.1
• 5ab4935 Fix duplicate export checking
• 44f0925 Mark release 4.0.0
• aa766d1 Filter out some duplicate author names in update_authors.sh
• e19dfcb disallow trailing comma in parens without arrow
• f5a6d81 Add tests for trailing commas in functions which have no arguments.
• 0e7a336 Add support of trailing commas in functions
• f508a83 Change default ecmaVersion to 7
• 36633f4 Update in-source documentation of some options
• 89b5c6d Remove trailing whitespace
• 78e8aa7 Make isAsyncFunction check for a non-identifier char after 'function'
• 7c75f92 Pass isAsync as argument to parseFunctionStatement
• b12370f Don't treat await as a keyword
• 7304648 add a comment.
• e700b29 fix allowing anonymous function declaration in the wrong

There are 81 commits in total. See the full diff.

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This pull request was created by greenkeeper.io.

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[coveralls]

Coverage remained the same at 100.0% when pulling 2464862 on greenkeeper-acorn-4.0.1 into 62498b4 on master.