javascript: improved parsing of anonymous functions

[jafl]

This is much simpler than #2005

[codecov]

Codecov Report

Merging #3437 (e9cff6d) into master (56813d1) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #3437   +/-   ##
=======================================
  Coverage   83.35%   83.35%           
=======================================
  Files         218      218           
  Lines       52510    52512    +2     
=======================================
+ Hits        43769    43772    +3     
+ Misses       8741     8740    -1     

Impacted Files	Coverage Δ
parsers/jscript.c	97.46% <100.00%> (+0.08%)	⬆️

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[jafl]

@masatake If I do a major refactor of parseStatement to break it up, will that cause major pain for any of your other jscript.c PR's?

[masatake]

Incredible!

[masatake]

Let's ignore the testing on NetBSD.

[masatake]

@masatake If I do a major refactor of parseStatement to break it up, will that cause major pain for any of your other jscript.c PR's?

I submitted #3433 and #3435. However, I don't care if your future pull request breaks them. Refactoring has a much higher priority!

[masatake]

BTW if you want to let users of the JavaScript parser know the design of the parser, you can write a man page for it. See https://docs.ctags.io/en/latest/man-pages.html and https://docs.ctags.io/en/latest/man/ctags-lang-python.7.html as examples.