From ae3989ebf056717684dba94f8f13d5fd4e77bc96 Mon Sep 17 00:00:00 2001
From: Xidorn Quan <me@upsuper.org>
Date: Tue, 14 Nov 2017 13:32:16 -0800
Subject: [PATCH] Serialize media rule and supports rule like Gecko.

---
 components/style/stylesheets/media_rule.rs    |  7 +------
 components/style/stylesheets/rule_list.rs     | 19 ++++++++++++++++++-
 components/style/stylesheets/supports_rule.rs |  7 +------
 3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/components/style/stylesheets/media_rule.rs b/components/style/stylesheets/media_rule.rs
index cce6dc2df3b..4c468b44cf6 100644
--- a/components/style/stylesheets/media_rule.rs
+++ b/components/style/stylesheets/media_rule.rs
@@ -46,12 +46,7 @@ impl ToCssWithGuard for MediaRule {
     where W: fmt::Write {
         dest.write_str("@media ")?;
         self.media_queries.read_with(guard).to_css(dest)?;
-        dest.write_str(" {")?;
-        for rule in self.rules.read_with(guard).0.iter() {
-            dest.write_str(" ")?;
-            rule.to_css(guard, dest)?;
-        }
-        dest.write_str(" }")
+        self.rules.read_with(guard).to_css_block(guard, dest)
     }
 }
 
diff --git a/components/style/stylesheets/rule_list.rs b/components/style/stylesheets/rule_list.rs
index 403c2839703..fbceb6c1a0b 100644
--- a/components/style/stylesheets/rule_list.rs
+++ b/components/style/stylesheets/rule_list.rs
@@ -7,7 +7,9 @@
 #[cfg(feature = "gecko")]
 use malloc_size_of::{MallocShallowSizeOf, MallocSizeOfOps};
 use servo_arc::{Arc, RawOffsetArc};
-use shared_lock::{DeepCloneParams, DeepCloneWithLock, Locked, SharedRwLock, SharedRwLockReadGuard};
+use shared_lock::{DeepCloneParams, DeepCloneWithLock, Locked};
+use shared_lock::{SharedRwLock, SharedRwLockReadGuard, ToCssWithGuard};
+use std::fmt;
 use stylesheets::{CssRule, RulesMutateError};
 use stylesheets::loader::StylesheetLoader;
 use stylesheets::rule_parser::State;
@@ -88,6 +90,21 @@ impl CssRules {
         self.0.remove(index);
         Ok(())
     }
+
+    /// Serializes this CSSRules to CSS text as a block of rules.
+    ///
+    /// This should be speced into CSSOM spec at some point. See
+    /// <https://github.com/w3c/csswg-drafts/issues/1985>
+    pub fn to_css_block<W>(&self, guard: &SharedRwLockReadGuard, dest: &mut W)
+        -> fmt::Result where W: fmt::Write
+    {
+        dest.write_str(" {")?;
+        for rule in self.0.iter() {
+            dest.write_str("\n  ")?;
+            rule.to_css(guard, dest)?;
+        }
+        dest.write_str("\n}")
+    }
 }
 
 /// A trait to implement helpers for `Arc<Locked<CssRules>>`.
diff --git a/components/style/stylesheets/supports_rule.rs b/components/style/stylesheets/supports_rule.rs
index 9b5d6a570d9..c65bc35cd7b 100644
--- a/components/style/stylesheets/supports_rule.rs
+++ b/components/style/stylesheets/supports_rule.rs
@@ -47,12 +47,7 @@ impl ToCssWithGuard for SupportsRule {
     where W: fmt::Write {
         dest.write_str("@supports ")?;
         self.condition.to_css(dest)?;
-        dest.write_str(" {")?;
-        for rule in self.rules.read_with(guard).0.iter() {
-            dest.write_str(" ")?;
-            rule.to_css(guard, dest)?;
-        }
-        dest.write_str(" }")
+        self.rules.read_with(guard).to_css_block(guard, dest)
     }
 }