diff --git a/components/style/values/specified/grid.rs b/components/style/values/specified/grid.rs
index 92dbc4fbcaa..82acf232298 100644
--- a/components/style/values/specified/grid.rs
+++ b/components/style/values/specified/grid.rs
@@ -9,7 +9,7 @@ use parser::{Parse, ParserContext};
 use std::ascii::AsciiExt;
 use std::fmt;
 use style_traits::ToCss;
-use values::{CSSFloat, HasViewportPercentage};
+use values::{CSSFloat, CustomIdent, HasViewportPercentage};
 use values::computed::{ComputedValueAsSpecified, Context, ToComputedValue};
 use values::specified::LengthOrPercentage;
 
@@ -18,7 +18,6 @@ use values::specified::LengthOrPercentage;
 /// A `<grid-line>` type.
 ///
 /// https://drafts.csswg.org/css-grid/#typedef-grid-row-start-grid-line
-#[allow(missing_docs)]
 pub struct GridLine {
     /// Flag to check whether it's a `span` keyword.
     pub is_span: bool,
@@ -306,3 +305,22 @@ impl<L: ToComputedValue> ToComputedValue for TrackSize<L> {
         }
     }
 }
+
+/// Parse the grid line names into a vector of owned strings.
+///
+/// https://drafts.csswg.org/css-grid/#typedef-line-names
+pub fn parse_line_names(input: &mut Parser) -> Result<Vec<String>, ()> {
+    input.expect_square_bracket_block()?;
+    input.parse_nested_block(|input| {
+        let mut values = vec![];
+        while let Ok(ident) = input.try(|i| i.expect_ident()) {
+            if CustomIdent::from_ident((&*ident).into(), &["span"]).is_err() {
+                return Err(())
+            }
+
+            values.push(ident.into_owned());
+        }
+
+        Ok(values)
+    })
+}