fix(gnoweb): show contents of source when javascript is disabled

[thehowl]

new result:

it wasn't working because the css in app.css was changed from display: none to opacity: 0.

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.92%. Comparing base (bdc9d0e) to head (a1358bf).
Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2860      +/-   ##
==========================================
+ Coverage   60.88%   60.92%   +0.03%     
==========================================
  Files         564      564              
  Lines       75269    75269              
==========================================
+ Hits        45830    45855      +25     
+ Misses      26062    26044      -18     
+ Partials     3377     3370       -7     

Flag	Coverage Δ
contribs/gnodev	61.46% <ø> (ø)
contribs/gnofaucet	14.46% <ø> (ø)
gno.land	67.17% <ø> (ø)
gnovm	65.77% <ø> (ø)
misc/genstd	80.54% <ø> (ø)
misc/logos	20.23% <ø> (+0.35%)	⬆️
tm2	62.11% <ø> (+0.09%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[gfanton]

Summoning @alexiscolin, just in case.