Bug 1352771 - Fix justify-content values. r=bholley

MozReview-Commit-ID: L4HFHTettLB

--HG--
extra : rebase_source : 33128c6bbbfbe2e2d77e3d4fdc87f6536296db21

servo/components/style/values/specified/align.rs

@@ -358,9 +358,9 @@ fn parse_content_distribution(input: &mut Parser) -> Result<AlignFlags, ()> {
     let ident = input.expect_ident()?;
     match_ignore_ascii_case! { &ident,
       "stretch" => Ok(ALIGN_STRETCH),
-      "space_between" => Ok(ALIGN_SPACE_BETWEEN),
+      "space-between" => Ok(ALIGN_SPACE_BETWEEN),
-      "space_around" => Ok(ALIGN_SPACE_AROUND),
+      "space-around" => Ok(ALIGN_SPACE_AROUND),
-      "space_evenly" => Ok(ALIGN_SPACE_EVENLY),
+      "space-evenly" => Ok(ALIGN_SPACE_EVENLY),
       _ => Err(())
     }
 }