Do not whitespace-strip <script>'s language attribute

[hiroshige-g]

• At least two implementers are interested (and none opposed):
  • Agreed on <script>'s language attribute is not whitespace-stripped in actual implementations #7923, and no need to change the implementations.
• Tests are written and can be reviewed and commented upon at:
  • https://wpt.fyi/results/html/semantics/scripting-1/the-script-element/script-type-and-language-js.html
• Implementation bugs are filed:
  • Not needed, this PR changes the spec to align with all three browser implementations.

Fixes #7923.

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/scripting.html ( diff )