Chain optimize map method

[gagandeepkalra]

fixes #2959

[codecov-io]

Codecov Report

Merging #2995 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2995      +/-   ##
==========================================
+ Coverage   93.83%   93.83%   +<.01%     
==========================================
  Files         369      369              
  Lines        7072     7073       +1     
  Branches      195      190       -5     
==========================================
+ Hits         6636     6637       +1     
  Misses        436      436

Impacted Files	Coverage Δ
core/src/main/scala/cats/data/Chain.scala	99.65% <100%> (ø)	⬆️

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[codecov-io]

Codecov Report

Merging #2995 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2995      +/-   ##
==========================================
+ Coverage   93.83%   93.83%   +<.01%     
==========================================
  Files         369      369              
  Lines        7072     7073       +1     
  Branches      195      190       -5     
==========================================
+ Hits         6636     6637       +1     
  Misses        436      436

Impacted Files	Coverage Δ
core/src/main/scala/cats/data/Chain.scala	99.65% <100%> (ø)	⬆️

---

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 241a7b9...649b160. Read the comment docs.

[kailuowang]

Thanks!