Fix some incorrect autocompletions for range and dynamic

[waf]

Fixes #279 (Range syntax completion) Fixes #231 ("dynamic" keyword completion)

[codecov[bot]]

Codecov Report

Merging #290 (938e68f) into main (e88921b) will increase coverage by 0.0%. The diff coverage is 91.6%.

@@          Coverage Diff          @@
##            main    #290   +/-   ##
=====================================
  Coverage   77.4%   77.5%           
=====================================
  Files         83      83           
  Lines       5564    5573    +9     
  Branches     731     733    +2     
=====================================
+ Hits        4312    4324   +12     
+ Misses       985     982    -3     
  Partials     267     267           

Files Changed	Coverage Δ
CSharpRepl.Services/Roslyn/RoslynServices.cs	84.0% <91.6%> (+0.1%)	:arrow_up:

... and 2 files with indirect coverage changes