Auto merge of #15612 - UnICorN21:master, r=canaltinova

fixed the wrong behavior of border-spacing

fixed the wrong behavior of border-spacing
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #15489.

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- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/style/properties/longhand/inherited_table.mako.rs

@@ -114,15 +114,11 @@ ${helpers.single_keyword("caption-side", "top bottom",
             Err(()) => (),
             Ok(length) => {
                 first = Some(length);
-                match specified::Length::parse_non_negative(input) {
-                    Err(()) => (),
-                    Ok(length) => second = Some(length),
+                if let Ok(len) = input.try(|input| specified::Length::parse_non_negative(input)) {
+                    second = Some(len);
                 }
             }
         }
-        if input.next().is_ok() {
-            return Err(())
-        }
         match (first, second) {
             (None, None) => Err(()),
             (Some(length), None) => {