From 7d813d8f25dd3804571e1016d81161af15f690ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Wed, 9 Aug 2017 16:23:49 +0200
Subject: [PATCH] style: Only zoom absolute lengths.

As silly as it may seem to specify font-sizes using viewport units, we weren't
handling zoom for them correctly either.

Bug: 1388588
Reviewed-by: Manishearth
MozReview-Commit-ID: 3Q6phYAu5CE
---
 .../style/properties/longhand/font.mako.rs    | 13 +++++++--
 components/style/values/computed/mod.rs       |  3 +-
 components/style/values/specified/text.rs     | 29 +++++++++++++------
 3 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/components/style/properties/longhand/font.mako.rs b/components/style/properties/longhand/font.mako.rs
index 8d8fcf017ec..96ba9199bf2 100644
--- a/components/style/properties/longhand/font.mako.rs
+++ b/components/style/properties/longhand/font.mako.rs
@@ -844,8 +844,11 @@ ${helpers.single_keyword_system("font-variant-caps",
         }
 
         /// Compute it against a given base font size
-        pub fn to_computed_value_against(&self, context: &Context, base_size: FontBaseSize)
-                                         -> NonNegativeAu {
+        pub fn to_computed_value_against(
+            &self,
+            context: &Context,
+            base_size: FontBaseSize,
+        ) -> NonNegativeAu {
             use values::specified::length::FontRelativeLength;
             match *self {
                 SpecifiedValue::Length(LengthOrPercentage::Length(
@@ -856,9 +859,13 @@ ${helpers.single_keyword_system("font-variant-caps",
                         NoCalcLength::ServoCharacterWidth(value))) => {
                     value.to_computed_value(base_size.resolve(context)).into()
                 }
-                SpecifiedValue::Length(LengthOrPercentage::Length(ref l)) => {
+                SpecifiedValue::Length(LengthOrPercentage::Length(
+                        NoCalcLength::Absolute(ref l))) => {
                     context.maybe_zoom_text(l.to_computed_value(context).into())
                 }
+                SpecifiedValue::Length(LengthOrPercentage::Length(ref l)) => {
+                    l.to_computed_value(context).into()
+                }
                 SpecifiedValue::Length(LengthOrPercentage::Percentage(pc)) => {
                     base_size.resolve(context).scale_by(pc.0).into()
                 }
diff --git a/components/style/values/computed/mod.rs b/components/style/values/computed/mod.rs
index a1206529f80..104c0fcd14a 100644
--- a/components/style/values/computed/mod.rs
+++ b/components/style/values/computed/mod.rs
@@ -135,8 +135,7 @@ impl<'a> Context<'a> {
         &self.builder
     }
 
-
-    /// Apply text-zoom if enabled
+    /// Apply text-zoom if enabled.
     #[cfg(feature = "gecko")]
     pub fn maybe_zoom_text(&self, size: NonNegativeAu) -> NonNegativeAu {
         // We disable zoom for <svg:text> by unsetting the
diff --git a/components/style/values/specified/text.rs b/components/style/values/specified/text.rs
index 8341d6236f1..08a59e87ff6 100644
--- a/components/style/values/specified/text.rs
+++ b/components/style/values/specified/text.rs
@@ -84,6 +84,7 @@ impl ToComputedValue for LineHeight {
 
     #[inline]
     fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        use values::specified::length::FontBaseSize;
         match *self {
             GenericLineHeight::Normal => {
                 GenericLineHeight::Normal
@@ -97,23 +98,33 @@ impl ToComputedValue for LineHeight {
             },
             GenericLineHeight::Length(ref non_negative_lop) => {
                 let result = match non_negative_lop.0 {
+                    LengthOrPercentage::Length(NoCalcLength::Absolute(ref abs)) => {
+                        context.maybe_zoom_text(abs.to_computed_value(context).into())
+                    }
                     LengthOrPercentage::Length(ref length) => {
-                        context.maybe_zoom_text(length.to_computed_value(context).into())
+                        length.to_computed_value(context).into()
                     },
                     LengthOrPercentage::Percentage(ref p) => {
-                        let font_relative_length =
-                            Length::NoCalc(NoCalcLength::FontRelative(FontRelativeLength::Em(p.0)));
-                        font_relative_length.to_computed_value(context).into()
+                        FontRelativeLength::Em(p.0)
+                            .to_computed_value(
+                                context,
+                                FontBaseSize::CurrentStyle,
+                            ).into()
                     }
                     LengthOrPercentage::Calc(ref calc) => {
                         let computed_calc = calc.to_computed_value_zoomed(context);
                         let font_relative_length =
-                            Length::NoCalc(NoCalcLength::FontRelative(
-                                FontRelativeLength::Em(computed_calc.percentage())));
+                            FontRelativeLength::Em(computed_calc.percentage())
+                                .to_computed_value(
+                                    context,
+                                    FontBaseSize::CurrentStyle,
+                                );
+
                         let absolute_length = computed_calc.unclamped_length();
-                        computed_calc.clamping_mode.clamp(
-                            absolute_length + font_relative_length.to_computed_value(context)
-                        ).into()
+                        computed_calc
+                            .clamping_mode
+                            .clamp(absolute_length + font_relative_length)
+                            .into()
                     }
                 };
                 GenericLineHeight::Length(result)