update goja to let-const branch

[mstoykov]

testing https://github.com/dop251/goja/tree/let-const

[codecov-io]

Codecov Report

Merging #1867 (0eb8ad9) into master (a85664b) will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1867      +/-   ##
==========================================
+ Coverage   71.48%   71.52%   +0.04%     
==========================================
  Files         180      180              
  Lines       13969    13969              
==========================================
+ Hits         9986     9992       +6     
+ Misses       3346     3340       -6     
  Partials      637      637              

Flag	Coverage Δ
ubuntu	71.47% <ø> (+0.02%)	⬆️
windows	71.11% <ø> (+0.02%)	⬆️

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Impacted Files	Coverage Δ
js/compiler/compiler.go	67.24% <ø> (ø)
lib/executor/vu_handle.go	95.23% <0.00%> (+1.90%)	⬆️
core/engine.go	93.03% <0.00%> (+1.99%)	⬆️

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[na--]

This seems like it should be closed in favor of #1904?