Given the right amount of time looking at the assembly of firefox isn't an impossible way to find out what it is doing.
A good counter example is the assembly of old nes games. I have read through some of them and you can even find nice commented versions of the main games source like mario, mario3, super mario etc. Reading the source is really eye opening. Some features in the game are very hard coded and fundamental to the code base changing it would be extremely hard. Other times you find fantastically elegant code. If anyone is interested in a treat go read the level loading asm for smb1.
A good counter example is the assembly of old nes games. I have read through some of them and you can even find nice commented versions of the main games source like mario, mario3, super mario etc. Reading the source is really eye opening. Some features in the game are very hard coded and fundamental to the code base changing it would be extremely hard. Other times you find fantastically elegant code. If anyone is interested in a treat go read the level loading asm for smb1.