Fix #14394: Changing style !important in webkit. Close gh-1385.
No ticket: Clean up uglifyjs compress options. Close gh-1382.
(cherry picked from commit e15627022f0c5e13a972baffb41f6f52ca4d3ec3)
Only set uglify options if not already the default
Ref 2263134b: Better identify potential JSON. Close gh-1401.