Fixes #17621.  Backport 560b804f-0ae3-0310-86f3-f6aa0a117693 to 1.8.
improve i18n preload to take advantage of partially flattened locales, fixes #17155

(cherry picked from commit 341e41f1797739449d883e8951cda54bde53417e)
Revert "Fix IE11 sniffing. Fixes #17311."

This reverts commit f58c0e19ce509398985908688a768c8fb41191b8.

(cherry picked from commit 477d62923e7cd1e32799395301f21c008dc55de6)
(cherry picked from commit 788afa04681010da261850e81f847089826c7dba)
Add Microsoft-recommended UA sniff for IE11

Fixes #17311

(cherry picked from commit 28c2050cbb7f69daa57bd66e3b740a16bb19fd75)
(cherry picked from commit bad851981604b4978e406edf11ab0a23b019a859)

Conflicts:
	sniff.js
Add Trident UA to match every other UA

Refs #17311

(cherry picked from commit bbe72ecd13f5604802b2498f3623e7c5961069f4)
(cherry picked from commit 769bfce2141826ed873d3eba3302227a08a43052)