Blocks Layout integration does not pass through cache metadata

thank you! That looks generally good, but I think we need to little more cleaning up before merge:

* getBlocks() code-comments need to be updated to reflect the new argument
* I think we should make the new argument $cacheableDependency optional, keep it NULL when omitted and only add cache-dependencies when passed. That way, we can keep up proper BC, in case someone would already use the method (what I doubt though)

Thanks for the feedback @fago! Updated to document the parameter and support BC.

I've also moved it to an MR.

thanks! I've found one issue with it though, please check!

doh! thanks @fago

Automatically closed - issue fixed for 2 weeks with no activity.