User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:71.0) Gecko/20100101 Firefox/71.0

Steps to reproduce:

1. Open the Data URL
   data:text/html;charset=UTF-8,%3Cstyle%3Ebody%7Btext-shadow%3A 0 0 1px rgba(25%2C 158%2C 189%2C .5)%7D%3C/style%3E%0Ahttps%3A//developer.mozilla.org/

Actual results:

Shadow color is too clear

Expected results:

Sorry for my bad English.

regression range:

2019-09-25T15:43:30: INFO : Narrowed inbound regression window from [ddb1fdf0, 96ce8d26] (3 builds) to [4c4c2559, 96ce8d26] (2 builds) (~1 steps left)
2019-09-25T15:43:30: DEBUG : Starting merge handling...
2019-09-25T15:43:30: DEBUG : Using url: https://hg.mozilla.org/integration/autoland/json-pushes?changeset=96ce8d267d27ed5a0b0b9cd7e105dcf90010d78f&full=1
2019-09-25T15:43:34: DEBUG : Found commit message:
Bug 1581934 - Restore the calculation for a more precise picture local rect. r=kvark,gw

Differential Revision: https://phabricator.services.mozilla.com/D46605

2019-09-25T15:43:34: DEBUG : Did not find a branch, checking all integration branches
2019-09-25T15:43:34: INFO : The bisection is done.
2019-09-25T15:43:34: INFO : Stopped

The effect is very subtle but I agree it is there.

This issue seems to have been fixed in bug 1589198.