Core: Faster Token.stringify

[RunDevelopment]

This removes temporary arrays in Token.stringify.

All these changes make Prism.highlight about 23% faster.

Benchmark

Found 6 cases with 13 files in total.
Test 2 candidates on highlight
Estimated duration: 4m 20s

------------------------------------------------------------

css

  ../../style.css (7 kB)
  | local              2.29ms ±  0%  171smp      
  | PrismJS@master     2.60ms ±  0%  174smp 1.13x

------------------------------------------------------------

css!+css-extras (css)

  ../../style.css (7 kB)
  | local              3.42ms ±  0%  164smp      
  | PrismJS@master     3.95ms ±  0%  161smp 1.16x

------------------------------------------------------------

javascript

  ../../components.json (24 kB)
  | local              8.50ms ±  1%  141smp      
  | PrismJS@master     9.23ms ±  0%  148smp 1.09x
  ../../package-lock.json (184 kB)
  | local             68.22ms ± 22%   71smp      
  | PrismJS@master   131.92ms ± 37%   33smp 1.93x
  ../../scripts/utopia.js (11 kB)
  | local              3.77ms ±  1%  159smp      
  | PrismJS@master     4.29ms ±  1%  159smp 1.14x
  prism.js (24 kB)
  | local              7.94ms ±  1%  151smp      
  | PrismJS@master     8.95ms ±  0%  153smp 1.13x
  prism.min.js (13 kB)
  | local              5.96ms ±  1%  161smp      
  | PrismJS@master     6.75ms ±  1%  158smp 1.13x

------------------------------------------------------------

json

  ../../components.json (24 kB)
  | local              7.78ms ±  1%  153smp      
  | PrismJS@master     9.37ms ±  1%  147smp 1.20x
  ../../package-lock.json (184 kB)
  | local             63.43ms ± 10%   76smp      
  | PrismJS@master   149.01ms ± 44%   27smp 2.35x

------------------------------------------------------------

markup

  ../../download.html (4 kB)
  | local              1.18ms ±  0%  179smp      
  | PrismJS@master     1.40ms ±  0%  173smp 1.18x
  ../../index.html (18 kB)
  | local              6.18ms ±  1%  155smp      
  | PrismJS@master     7.14ms ±  1%  149smp 1.16x

------------------------------------------------------------

markup!+css+javascript (markup)

  ../../download.html (4 kB)
  | local              1.88ms ±  1%  168smp      
  | PrismJS@master     2.15ms ±  1%  169smp 1.14x
  ../../index.html (18 kB)
  | local              7.12ms ±  1%  149smp      
  | PrismJS@master     8.13ms ±  1%  147smp 1.14x

------------------------------------------------------------

summary
                  best  worst  avg rel  avg rel norm
  local             13      0    1.00x         1.00x
  PrismJS@master     0     13    1.30x         1.30x

[mAAdhaTTah]

Nice!