From 7fb470c373161b8f0dd4cd7d27141032e904df63 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Fri, 2 Feb 2018 15:00:32 +0100
Subject: [PATCH] style: Remove some uses of StyleBuilder::for_derived_style.

for_derived_style(default_values) is effectively for_inheritance(default_values).

MozReview-Commit-ID: DfTeD49uTlp
---
 .../style/properties/properties.mako.rs       | 12 ++++---
 components/style/stylesheets/viewport_rule.rs |  2 +-
 components/style/values/computed/mod.rs       |  2 +-
 ports/geckolib/glue.rs                        | 31 ++++++-------------
 4 files changed, 20 insertions(+), 27 deletions(-)

diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index 73c0cd6498c..825a3c737cc 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -2783,8 +2783,12 @@ impl<'a> StyleBuilder<'a> {
         self.flags.contains(ComputedValueFlags::IS_STYLE_IF_VISITED)
     }
 
-    /// Creates a StyleBuilder holding only references to the structs of `s`, in
-    /// order to create a derived style.
+    /// NOTE(emilio): This is done so we can compute relative units with respect
+    /// to the parent style, but all the early properties / writing-mode / etc
+    /// are already set to the right ones on the kid.
+    ///
+    /// Do _not_ actually call this to construct a style, this should mostly be
+    /// used for animations.
     pub fn for_derived_style(
         device: &'a Device,
         style_to_derive_from: &'a ComputedValues,
@@ -2805,11 +2809,11 @@ impl<'a> StyleBuilder<'a> {
             reset_style,
             pseudo,
             modified_reset: false,
-            rules: None, // FIXME(emilio): Dubious...
+            rules: None,
             custom_properties: style_to_derive_from.custom_properties().cloned(),
             writing_mode: style_to_derive_from.writing_mode,
             flags: style_to_derive_from.flags,
-            visited_style: style_to_derive_from.clone_visited_style(),
+            visited_style: None,
             % for style_struct in data.active_style_structs():
             ${style_struct.ident}: StyleStructRef::Borrowed(
                 style_to_derive_from.${style_struct.name_lower}_arc()
diff --git a/components/style/stylesheets/viewport_rule.rs b/components/style/stylesheets/viewport_rule.rs
index e50d9f1720b..f4bb2fb39df 100644
--- a/components/style/stylesheets/viewport_rule.rs
+++ b/components/style/stylesheets/viewport_rule.rs
@@ -720,7 +720,7 @@ impl MaybeNew for ViewportConstraints {
         let mut conditions = RuleCacheConditions::default();
         let context = Context {
             is_root_element: false,
-            builder: StyleBuilder::for_derived_style(device, default_values, None, None),
+            builder: StyleBuilder::for_inheritance(device, default_values, None),
             font_metrics_provider: &provider,
             cached_system_font: None,
             in_media_query: false,
diff --git a/components/style/values/computed/mod.rs b/components/style/values/computed/mod.rs
index f3f129fe8fa..5e1c519c7c4 100644
--- a/components/style/values/computed/mod.rs
+++ b/components/style/values/computed/mod.rs
@@ -179,7 +179,7 @@ impl<'a> Context<'a> {
 
         let context = Context {
             is_root_element: false,
-            builder: StyleBuilder::for_derived_style(device, default_values, None, None),
+            builder: StyleBuilder::for_inheritance(device, default_values, None),
             font_metrics_provider: &provider,
             cached_system_font: None,
             in_media_query: true,
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 518c5f46964..ba2614f7dcd 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -2318,30 +2318,19 @@ pub extern "C" fn Servo_ComputedValues_Inherit(
     let atom = Atom::from(pseudo_tag);
     let pseudo = PseudoElement::from_anon_box_atom(&atom)
         .expect("Not an anon-box? Gah!");
-    let style = if let Some(reference) = parent_style_context {
-        let mut style = StyleBuilder::for_inheritance(
-            data.stylist.device(),
-            reference,
-            Some(&pseudo)
-        );
+    let device = data.stylist.device();
 
-        if for_text {
-            StyleAdjuster::new(&mut style)
-                .adjust_for_text();
-        }
+    let mut style = StyleBuilder::for_inheritance(
+        data.stylist.device(),
+        parent_style_context.unwrap_or_else(|| device.default_computed_values()),
+        Some(&pseudo)
+    );
 
-        style.build()
-    } else {
-        debug_assert!(!for_text);
-        StyleBuilder::for_derived_style(
-            data.stylist.device(),
-            data.default_computed_values(),
-            /* parent_style = */ None,
-            Some(&pseudo),
-        ).build()
-    };
+    if for_text {
+        StyleAdjuster::new(&mut style).adjust_for_text();
+    }
 
-    style.into()
+    style.build().into()
 }
 
 #[no_mangle]