[webkit-help] How does /DerivedSources/HTMLNames.* get generated

[n179911]

Hi,

Can you please tell me how does these files get generated?
./DerivedSources/HTMLNames.cpp
./DerivedSources/HTMLNames.h

Does it look up some files to determine what are the attributes, names
for generation?
If yes, can you please tell me what is that file?

Thank you.