add FileReader Web API to js dom (#14105)
add FileReader Web API to js dom (#14105)

* add FileReader to js dom
* minor improvement
Co-authored-by: cooldome <eb527cc30030e609469738143c7b861ed0290905@bk.ru>
dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim