Auto merge of #15524 - BorisChiou:animation/drop_RestyleWithAddedDeclaration, r=Manishearth

stylo: Drop Servo_RestyleWithAddedDeclaration

This is the servo-side change for [bug 1338087](https://bugzilla.mozilla.org/show_bug.cgi?id=1338087). r=@Manishearth

---
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] `./mach test-stylo` does not report any errors
- [X] These changes fix [bug 1338087](https://bugzilla.mozilla.org/show_bug.cgi?id=1338087).
- [X] These changes do not require tests because there are existing tests for this in mozilla-central

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/15524)
<!-- Reviewable:end -->

components/style/gecko_bindings/bindings.rs

@@ -1271,14 +1271,6 @@ extern "C" {
                                principal: *mut ThreadSafePrincipalHolder)
      -> RawServoDeclarationBlockStrong;
 }
-extern "C" {
-    pub fn Servo_RestyleWithAddedDeclaration(set: RawServoStyleSetBorrowed,
-                                             declarations:
-                                                 RawServoDeclarationBlockBorrowed,
-                                             previous_style:
-                                                 ServoComputedValuesBorrowed)
-     -> ServoComputedValuesStrong;
-}
 extern "C" {
     pub fn Servo_AnimationValues_Populate(arg1:
                                               RawGeckoAnimationValueListBorrowedMut,

ports/geckolib/glue.rs

@@ -64,10 +64,10 @@ use style::gecko_properties::style_structs;
 use style::keyframes::KeyframesStepValue;
 use style::parallel;
 use style::parser::{ParserContext, ParserContextExtraData};
-use style::properties::{CascadeFlags, ComputedValues, Importance, PropertyDeclaration};
+use style::properties::{ComputedValues, Importance, PropertyDeclaration};
 use style::properties::{PropertyDeclarationParseResult, PropertyDeclarationBlock, PropertyId};
-use style::properties::{apply_declarations, parse_one_declaration};
 use style::properties::animated_properties::{AnimationValue, Interpolate, TransitionProperty};
+use style::properties::parse_one_declaration;
 use style::restyle_hints::RestyleHint;
 use style::selector_parser::PseudoElementCascadeType;
 use style::sequential;
@@ -331,36 +331,6 @@ pub extern "C" fn Servo_AnimationValue_Release(anim: RawServoAnimationValueBorro
     unsafe { AnimationValue::release(anim) };
 }
 
-#[no_mangle]
-pub extern "C" fn Servo_RestyleWithAddedDeclaration(raw_data: RawServoStyleSetBorrowed,
-                                                    declarations: RawServoDeclarationBlockBorrowed,
-                                                    previous_style: ServoComputedValuesBorrowed)
-  -> ServoComputedValuesStrong
-{
-    let previous_style = ComputedValues::as_arc(&previous_style);
-    let declarations = RwLock::<PropertyDeclarationBlock>::as_arc(&declarations);
-
-    let guard = declarations.read();
-
-    let declarations = || {
-        guard.declarations.iter().rev().map(|&(ref decl, _importance)| decl)
-    };
-
-    let data = PerDocumentStyleData::from_ffi(raw_data).borrow();
-
-    // FIXME (bug 1303229): Use the actual viewport size here
-    let computed = apply_declarations(Size2D::new(Au(0), Au(0)),
-                                      /* is_root_element = */ false,
-                                      declarations,
-                                      previous_style,
-                                      data.default_computed_values(),
-                                      None,
-                                      Box::new(StdoutErrorReporter),
-                                      None,
-                                      CascadeFlags::empty());
-    Arc::new(computed).into_strong()
-}
-
 #[no_mangle]
 pub extern "C" fn Servo_StyleWorkerThreadCount() -> u32 {
     *NUM_THREADS as u32