Auto merge of #18498 - upsuper:enum-keyword-exhaustive, r=emilio

Use exhaustive match for cloning keyword value by default for property using enum class

rather than casting them to `u8` then do inexhaustive match.

I don't see why we couldn't do this.

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components/style/properties/longhand/box.mako.rs

@@ -1793,7 +1793,6 @@ ${helpers.single_keyword("-moz-orient",
                           gecko_ffi_name="mOrient",
                           gecko_enum_prefix="StyleOrient",
                           spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/-moz-orient)",
-                          gecko_inexhaustive="True",
                           animation_value_type="discrete")}
 
 <%helpers:longhand name="will-change" products="gecko" animation_value_type="discrete"