As some may be aware, Java 8 does not play well with versions of forge after Minecraft 1.6 but before Forge 1230. Since updating a pack to 1.7.10 can be a lot of work, some pack owners have ignored this issue for a little while now. However, there has been a mod available for a little while called LegacyJavaFixer, which allows older versions of forge to work with Java 1.8 properly. You can get it here. Putting that mod into your pack will allow Java 8 users to play your pack.
Packs that are not compatible with Java 8 generate a lot of frustration for Platform users, they produce a lot of reports to clear for us, and we want them to update. It's easier than ever now, just add the LegacyJavaFixer to your pack, or update to Forge 1230. Either of these will work.
For this reason, beginning on February 9, we will be treating packs that are not compatible with Java 8 as nonfunctioning. That means that if we get a report from a Java 8 users saying that your pack doesn't work, your pack will be disabled until you address the issue. During that time, users will see your pack as Offline in the launcher, your pack will not appear in search or the trending list. If you're interested in getting your pack popular, being disabled can be very damaging. That is why you need to address this issue before February 9. If you have any questions about how to fix your pack, please ask here, or join us on reddit or IRC.