[feature](text-overflow): Enable text-overflow for layout-2020

Signed-off-by: Desiatkin Dmitrii <[email protected]>

Author: d-desiatkin

style/properties/longhands/text.mako.rs

@@ -9,7 +9,6 @@ ${helpers.predefined_type(
     "TextOverflow",
     "computed::TextOverflow::get_initial_value()",
     engines="gecko servo",
-    servo_pref="layout.legacy_layout",
     animation_type="discrete",
     boxed=True,
     spec="https://drafts.csswg.org/css-ui/#propdef-text-overflow",