Wrap some generated do expressions in parens

[zjmiller]

Q	A
Patch: Bug Fix?	yes
Major: Breaking Change?	no
Minor: New Feature?	no
Deprecations?	no
Spec Compliancy?	no
Tests Added/Pass?	yes
Fixed Tickets	none
License	MIT
Doc PR	no
Dependency Changes	no

A do expression at the beginning of a statement needs to be wrapped in parentheses. Otherwise the parser will think it is a do...while statement. I modified babel-generator to add these parentheses.

[mention-bot]

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

[oleksandr-kuzmenko]

=)
https://github.com/babel/babel/pull/5338/files
it looks like we have added new files with the same name

[zjmiller]

Ah cool. I'll take out the duplicate files from my PR and just leave the parentheses-related stuff.

[codecov-io]

Codecov Report

Merging #5339 into master will increase coverage by 0.04%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #5339      +/-   ##
==========================================
+ Coverage   89.44%   89.48%   +0.04%     
==========================================
  Files         204      204              
  Lines        9949     9951       +2     
  Branches     2689     2689              
==========================================
+ Hits         8899     8905       +6     
+ Misses       1050     1046       -4

Impacted Files	Coverage Δ
packages/babel-generator/src/node/parentheses.js	92.5% <100%> (+0.12%)	✅
...ages/babel-generator/src/generators/expressions.js	96.15% <ø> (+3.07%)	✅

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 07dd2b1...dfd266e. Read the comment docs.