Auto merge of #16144 - emilio:number-calc, r=heycam

style: Make numbers keep track of whether they were specified as calc().

Fixes #15960

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ports/geckolib/glue.rs

@@ -1202,7 +1202,7 @@ pub extern "C" fn Servo_DeclarationBlock_SetPixelValue(declarations:
         BorderSpacing => Box::new(
             BorderSpacing {
                 horizontal: nocalc.into(),
-                vertical: nocalc.into(),
+                vertical: None,
             }
         ),
     };