Update key.js

It is supposed to be OR with 0x4 instead of 0x5.
Update key.js

Possible mistype. Bit 3 mask was 0x5 (b0101), it should be 0x4 (b0100).
Merge remote-tracking branch 'origin/patch-1'
Merge remote-tracking branch 'origin/patch-2'
Merge branch 'master' of https://github.com/gabrieloshiro/jsGB