Simplify Text Shadowing by Using NSShadowAttributeName

[garrettmoon]

From @Adlai-Holler on October 30, 2016 16:45

Currently our shadowing is implemented by ASTextKitShadower. We can simplify our text shadowing (and improve performance!) by using NSShadowAttributeName. During our rendering, if they specify a shadow on the node, we should add the shadow attribute into the string (anywhere it isn't already set.)

Considerations:

• We should check if NSShadowAttributeName affects sizing calculations – whether the shadow outset is included automatically or not.
• We should avoid allocating NSShadow objects whenever possible.

Copied from original issue: facebookarchive/AsyncDisplayKit#2510

[garrettmoon]

From @hannahmbanana on February 9, 2017 19:59

I for one, am SUPER EXCITED to see @Adlai-Holler's new ASTextNode improvements coming soon in Spring '17!

[garrettmoon]

From @Adlai-Holler on February 10, 2017 7:19

Me too! God that guy is so handsome!