Auto merge of #17775 - michael-p:rename-stylearc-to-servo-arc, r=emilio

Replace all uses of the style::stylearc alias with servo_arc.

The `stylearc` alias is left there temporarilly and will be removed completely in a later commit/PR where also `components/style/gecko/generated/structs_{debug|release}.rs` are re-generated (they still use the old alias).

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<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #17768  (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because no new features / only refactoring

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components/style/gecko_bindings/sugar/ownership.rs

@@ -4,11 +4,11 @@
 
 //! Helpers for different FFI pointer kinds that Gecko's FFI layer uses.
 
+use servo_arc::{Arc, RawOffsetArc};
 use std::marker::PhantomData;
 use std::mem::{forget, transmute};
 use std::ops::{Deref, DerefMut};
 use std::ptr;
-use stylearc::{Arc, RawOffsetArc};
 
 /// Indicates that a given Servo type has a corresponding Gecko FFI type.
 pub unsafe trait HasFFI : Sized + 'static {

components/style/gecko_bindings/sugar/refptr.rs

@@ -6,10 +6,10 @@
 
 use gecko_bindings::structs;
 use gecko_bindings::sugar::ownership::HasArcFFI;
+use servo_arc::Arc;
 use std::{mem, ptr};
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut};
-use stylearc::Arc;
 
 /// Trait for all objects that have Addref() and Release
 /// methods and can be placed inside RefPtr<T>