Change gif loop behaviour to works like most of the modern browsers

[pawlowskim]

Hello. I was testing YYImage with react-native port (https://www.npmjs.com/package/react-native-yyimage) against loop behaviour. I found out that, library sets infinity loops when there is no loop count (Animation iterations from exiftool) in gif metadata. Other browsers sets default loop count = 1 when no metadata available. I have tested the same looped gifs on android, chrome, safari opera and mozilla FF and iOS. I don't know if you want to change default behaviour of YYImage but for my needs I changed it to works like the same way like on:

• android
• chrome
• safari
• opera

[dreampiggy]

This is the GIF in browser behavior, but will break APNG and Animated WebP behavior in browser. You can check that both these set 0 by default to infinity loop in Chrome 59, Safari(Not Animated WebP), firefox.. So a better solution is to set that loop count on your logic level but not the Decoder Level.. You can override that loop count when using GIF.