servo: Merge #8855 - move FocusType enum to the script crate (from romankl:move-focus-enum); r=Ms2ger

This commit moves the FocusType enum to the script crate and replaces all usages with the new `usage`.

Fixes #8840

Source-Repo: https://github.com/servo/servo
Source-Revision: e16c930f36582f40da4736f88675f559e7e47098

servo/components/msg/constellation_msg.rs

@@ -213,13 +213,6 @@ bitflags! {
     }
 }
 
-/// Specifies the type of focus event that is sent to a pipeline
-#[derive(Copy, Clone, PartialEq)]
-pub enum FocusType {
-    Element,    // The first focus message - focus the element itself
-    Parent,     // Focusing a parent element (an iframe)
-}
-
 /// Specifies the information required to load a URL in an iframe.
 #[derive(Deserialize, Serialize)]
 pub struct IframeLoadInfo {