[Refactor] improve performance for detecting class components

[golopot]

Benchmark on the eslint repo with extends: plugin:react/recommended and time npx eslint . (real time):

	before	after
run 1	8.0s	7.3s
run 2	7.8s	7.4s
run 3	8.0s	7.3s

Benchmark with TIMING=10 npx eslint .:

Before:

Rule                           | Time (ms) | Relative
:------------------------------|----------:|--------:
react/no-deprecated            |   762.467 |    21.0%
react/no-direct-mutation-state |   648.951 |    17.9%
react/display-name             |   635.527 |    17.5%
react/no-string-refs           |   531.934 |    14.7%
react/prop-types               |   387.259 |    10.7%
react/require-render-return    |   382.931 |    10.6%
react/no-children-prop         |   165.876 |     4.6%
react/jsx-no-comment-textnodes |    49.452 |     1.4%
react/no-unescaped-entities    |    19.529 |     0.5%
react/jsx-key                  |    14.197 |     0.4%

After:

Rule                           | Time (ms) | Relative
:------------------------------|----------:|--------:
react/no-deprecated            |   531.083 |    21.5%
react/no-direct-mutation-state |   466.098 |    18.8%
react/display-name             |   427.566 |    17.3%
react/no-string-refs           |   313.779 |    12.7%
react/require-render-return    |   251.905 |    10.2%
react/prop-types               |   245.300 |     9.9%
react/no-children-prop         |   141.999 |     5.7%
react/jsx-no-comment-textnodes |    39.487 |     1.6%
react/no-unescaped-entities    |    17.461 |     0.7%
react/jsx-key                  |    12.571 |     0.5%

[codecov-commenter]

Codecov Report

Merging #3267 (161317e) into master (8992a2b) will decrease coverage by 0.00%.
The diff coverage is 92.30%.

@@            Coverage Diff             @@
##           master    #3267      +/-   ##
==========================================
- Coverage   97.69%   97.68%   -0.01%     
==========================================
  Files         121      121              
  Lines        8583     8593      +10     
  Branches     3120     3127       +7     
==========================================
+ Hits         8385     8394       +9     
- Misses        198      199       +1     

Impacted Files	Coverage Δ
lib/util/Components.js	98.70% <92.30%> (-0.17%)	⬇️

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[ljharb]

Changes in general look good!

[ljharb]

is there a speed improvement from caching this non-global regex at module level?

[golopot]

I tried and didn't see a speed improvement. I suppose the compiler can compile the regexp once and reuse it afterwards.

[golopot]

This contrasts with the previous line RegExp(^(${pragma}\.)?(Pure)?Component$) where v8 have to compile the regexp at runtime at every function call.

[ljharb]

we'll land it as-is then for now