Auto merge of #17532 - bholley:set_explicit_style, r=emilio

stylo: Attach styles explicitly to generated content

https://bugzilla.mozilla.org/show_bug.cgi?id=1376245

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ports/geckolib/glue.rs

@@ -1493,6 +1493,20 @@ pub extern "C" fn Servo_ResolvePseudoStyle(element: RawGeckoElementBorrowed,
     }
 }
 
+#[no_mangle]
+pub extern "C" fn Servo_SetExplicitStyle(element: RawGeckoElementBorrowed,
+                                         style: ServoComputedValuesBorrowed)
+{
+    let element = GeckoElement(element);
+    let style = ComputedValues::as_arc(&style);
+    debug!("Servo_SetExplicitStyle: {:?}", element);
+    // We only support this API for initial styling. There's no reason it couldn't
+    // work for other things, we just haven't had a reason to do so.
+    debug_assert!(element.get_data().is_none());
+    let mut data = unsafe { element.ensure_data() }.borrow_mut();
+    data.styles.primary = Some(style.clone());
+}
+
 #[no_mangle]
 pub extern "C" fn Servo_HasAuthorSpecifiedRules(element: RawGeckoElementBorrowed,
                                                 rule_type_mask: u32,
@@ -1627,6 +1641,14 @@ pub extern "C" fn Servo_ComputedValues_GetVisitedStyle(values: ServoComputedValu
     }
 }
 
+#[no_mangle]
+pub extern "C" fn Servo_ComputedValues_SpecifiesAnimationsOrTransitions(values: ServoComputedValuesBorrowed)
+                                                                        -> bool {
+    let values = ComputedValues::as_arc(&values);
+    let b = values.get_box();
+    b.specifies_animations() || b.specifies_transitions()
+}
+
 /// See the comment in `Device` to see why it's ok to pass an owned reference to
 /// the pres context (hint: the context outlives the StyleSet, that holds the
 /// device alive).