Auto merge of #16253 - hiikezoe:baseline-fix, r=Manishearth

Fix handling of baseline

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This is a PR of https://bugzilla.mozilla.org/show_bug.cgi?id=1352781

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- [X] `./mach test-tidy` does not report any errors

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- [X] There are tests for these changes
There are a bunch of css reftests, but I am not sure how servo handles them. Let's see what happens. I guess I need to modify some metadata.

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components/style/values/specified/align.rs

@@ -80,8 +80,8 @@ impl ToCss for AlignFlags {
             ALIGN_CENTER => "center",
             ALIGN_LEFT => "left",
             ALIGN_RIGHT => "left",
-            ALIGN_BASELINE => "right",
+            ALIGN_BASELINE => "baseline",
-            ALIGN_LAST_BASELINE => "baseline",
+            ALIGN_LAST_BASELINE => "last baseline",
             ALIGN_STRETCH => "stretch",
             ALIGN_SELF_START => "self-start",
             ALIGN_SELF_END => "self-end",
@@ -322,33 +322,63 @@ impl Parse for JustifyItems {
 
 // auto | normal | stretch | <baseline-position>
 fn parse_auto_normal_stretch_baseline(input: &mut Parser) -> Result<AlignFlags, ()> {
+    if let Ok(baseline) = input.try(|input| parse_baseline(input)) {
+        return Ok(baseline);
+    }
+
     let ident = input.expect_ident()?;
     match_ignore_ascii_case! { &ident,
         "auto" => Ok(ALIGN_AUTO),
         "normal" => Ok(ALIGN_NORMAL),
         "stretch" => Ok(ALIGN_STRETCH),
-        "baseline" => Ok(ALIGN_BASELINE),
         _ => Err(())
     }
 }
 
 // normal | stretch | <baseline-position>
 fn parse_normal_stretch_baseline(input: &mut Parser) -> Result<AlignFlags, ()> {
+    if let Ok(baseline) = input.try(|input| parse_baseline(input)) {
+        return Ok(baseline);
+    }
+
     let ident = input.expect_ident()?;
     match_ignore_ascii_case! { &ident,
         "normal" => Ok(ALIGN_NORMAL),
         "stretch" => Ok(ALIGN_STRETCH),
-        "baseline" => Ok(ALIGN_BASELINE),
         _ => Err(())
     }
 }
 
 // normal | <baseline-position>
 fn parse_normal_or_baseline(input: &mut Parser) -> Result<AlignFlags, ()> {
+    if let Ok(baseline) = input.try(|input| parse_baseline(input)) {
+        return Ok(baseline);
+    }
+
     let ident = input.expect_ident()?;
     match_ignore_ascii_case! { &ident,
         "normal" => Ok(ALIGN_NORMAL),
+        _ => Err(())
+    }
+}
+
+// <baseline-position>
+fn parse_baseline(input: &mut Parser) -> Result<AlignFlags, ()> {
+    let ident = input.expect_ident()?;
+    match_ignore_ascii_case! { &ident,
         "baseline" => Ok(ALIGN_BASELINE),
+        "first" => {
+            if input.try(|input| input.expect_ident_matching("baseline")).is_ok() {
+                return Ok(ALIGN_BASELINE);
+            }
+            Err(())
+        },
+        "last" => {
+            if input.try(|input| input.expect_ident_matching("baseline")).is_ok() {
+                return Ok(ALIGN_LAST_BASELINE);
+            }
+            Err(())
+        },
         _ => Err(())
     }
 }