Update babylon beta 4

[hzoo]

Ref #5367

[mention-bot]

@hzoo, thanks for your PR! By analyzing the history of the files in this pull request, we identified @dlwalsh, @loganfsmyth and @forivall to be potential reviewers.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (7.0@3ff77a6). Click here to learn what that means.
The diff coverage is 100%.

@@          Coverage Diff           @@
##             7.0    #5399   +/-   ##
======================================
  Coverage       ?   85.35%           
======================================
  Files          ?      204           
  Lines          ?     9561           
  Branches       ?     2696           
======================================
  Hits           ?     8161           
  Misses         ?      909           
  Partials       ?      491

Impacted Files	Coverage Δ
...babel-helper-remap-async-to-generator/src/index.js	89.47% <100%> (ø)

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