Fix sourceMappingURL in compressed/minified files

[rbague]

As of right now, the SourceMappingUrls compiler does not work with sass compressed CSS files, as the regex ...

propshaft/lib/propshaft/compiler/source_mapping_urls.rb

Line 6 in 26082d0

SOURCE_MAPPING_PATTERN = %r{^(//|/\*)# sourceMappingURL=(.+\.map)}

... used to detect sourceMappingURLS expects the comment to be in a new line (which is not the case in the compressed mode, as it outputs everything in a single line).

Following what is stated in the Source Map Proposal, that the annotation must be at the end of the source, I've updated the regex so instead of looking for the comment at the start of a line, it looks for it at the end of the source, and included tests for compressed JS and CSS files.

The new regex should cover all the possible scenarios of how source map annotations are being appended to the generated CSS/JS file:

• esbuild
• PostCSS
• Sass
  • Even in legacy mode

Let me know if there is anything I need to update to get this merged.

[aaronjensen]

Is this a duplicate of #133?

[rbague]

Closing this now that #133 is merged and solves the same problem