[Fixes #6817] Displaying document 'image/tiff' is broken because bro…

[afabiani]

…wsers do not support 'img' src tag

Checklist

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[codecov]

Codecov Report

Merging #6818 (e320a65) into master (d888a6c) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #6818      +/-   ##
==========================================
+ Coverage   51.65%   51.67%   +0.01%     
==========================================
  Files         573      573              
  Lines       40807    40822      +15     
  Branches     5496     5500       +4     
==========================================
+ Hits        21080    21095      +15     
  Misses      18397    18397              
  Partials     1330     1330