fix(fetch): prevent Illegal invocations of the FileLike class

[RaisinTen]

Signed-off-by: Darshan Sen [email protected]

[codecov-commenter]

Codecov Report

Merging #1207 (8b1c5a1) into main (a54b8f5) will decrease coverage by 0.27%.
The diff coverage is 14.28%.

@@            Coverage Diff             @@
##             main    #1207      +/-   ##
==========================================
- Coverage   93.78%   93.50%   -0.28%     
==========================================
  Files          43       43              
  Lines        4021     4035      +14     
==========================================
+ Hits         3771     3773       +2     
- Misses        250      262      +12     

Impacted Files	Coverage Δ
lib/fetch/file.js	52.08% <14.28%> (-15.57%)	⬇️

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[mcollina]

Why is this needed? Is it part of the spec?

[RaisinTen]

Why is this needed?

I added the validators because the rest of the methods both in File (even the ones inherited from require('buffer').Blob) and FileLike had them and I couldn't think of a good reason why we shouldn't validate this.

Is it part of the spec?

Is FileLike a part of the spec? It was added in #1110 without any spec link. I was looking for it in https://w3c.github.io/FileAPI/#dfn-file but I couldn't find it. Do you have a link to the FileLike spec?

[mcollina]

lgtm