[CSS] Add stub for font-variation-settings

This stub is added because websites insist on considering this
very hardware-dependent and O.S.-variable low-level font-control
as a "critical feature" which it isn't as there is 0 guarantee
that font variation settings are supported or honored by any
operating system used by the client.

On top this is a WD status feature that sites shouldn't be using, and
the feature itself is strongly discouraged for use in favor of standard
CSS font manipulation keywords like `font-weight`.

6 files changed, 45 insertions, 0 deletions

diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index a8309314f..556e35406 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -1056,6 +1056,7 @@ protected:
   bool ParseOneFamily(nsAString& aFamily, bool& aOneKeyword, bool& aQuoted);
   bool ParseFamily(nsCSSValue& aValue);
   bool ParseFontFeatureSettings(nsCSSValue& aValue);
+  bool ParseFontVariationSettings(nsCSSValue& aValue);
   bool ParseFontSrc(nsCSSValue& aValue);
   bool ParseFontSrcFormat(InfallibleTArray<nsCSSValue>& values);
   bool ParseFontRanges(nsCSSValue& aValue);
@@ -12092,6 +12093,8 @@ CSSParserImpl::ParseSingleValuePropertyByFunction(nsCSSValue& aValue,
       return ParseFontVariantNumeric(aValue);
     case eCSSProperty_font_feature_settings:
       return ParseFontFeatureSettings(aValue);
+    case eCSSProperty_font_variation_settings:
+      return ParseFontVariationSettings(aValue);
     case eCSSProperty_font_weight:
       return ParseFontWeight(aValue);
     case eCSSProperty_image_orientation:
@@ -15315,6 +15318,19 @@ CSSParserImpl::ParseFontFeatureSettings(nsCSSValue& aValue)
   return true;
 }
 
+bool

+CSSParserImpl::ParseFontVariationSettings(nsCSSValue& aValue)

+{

+  // TODO: Actually implement this.

+  

+  // This stub is here because websites insist on considering this

+  // very hardware-dependent and O.S.-variable low-level font-control

+  // as a "critical feature" which it isn't as there is 0 guarantee

+  // that font variation settings are supported or honored by any

+  // operating system used by the client.

+  return true;

+}
+
 bool
 CSSParserImpl::ParseListStyle()
 {
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 07db6d3dd..411f982a4 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -2037,6 +2037,20 @@ CSS_PROP_FONT(
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
 CSS_PROP_FONT(
+    font-variation-settings,
+    font_variation_settings,
+    FontVariationSettings,
+    CSS_PROPERTY_PARSE_VALUE |
+        CSS_PROPERTY_VALUE_PARSER_FUNCTION |
+        CSS_PROPERTY_VALUE_LIST_USES_COMMAS |
+        CSS_PROPERTY_APPLIES_TO_FIRST_LETTER_AND_FIRST_LINE |
+        CSS_PROPERTY_APPLIES_TO_PLACEHOLDER,
+    "layout.css.font-variations.stub",
+    0,
+    nullptr,
+    CSS_PROP_NO_OFFSET,
+    eStyleAnimType_Discrete)
+CSS_PROP_FONT(
     font-weight,
     font_weight,
     FontWeight,
diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index 647f7f6dc..c717d59c8 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -1620,6 +1620,16 @@ nsComputedDOMStyle::DoGetFontFeatureSettings()
 }
 
 already_AddRefed<CSSValue>
+nsComputedDOMStyle::DoGetFontVariationSettings()
+{
+  // TODO: This is still a stub, always returning "normal"
+  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
+
+  val->SetIdent(eCSSKeyword_normal);
+  return val.forget();
+}
+
+already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetFontKerning()
 {
   RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
diff --git a/layout/style/nsComputedDOMStyle.h b/layout/style/nsComputedDOMStyle.h
index 7fbf49afe..e94d8dbf6 100644
--- a/layout/style/nsComputedDOMStyle.h
+++ b/layout/style/nsComputedDOMStyle.h
@@ -251,6 +251,7 @@ private:
   already_AddRefed<CSSValue> DoGetColor();
   already_AddRefed<CSSValue> DoGetFontFamily();
   already_AddRefed<CSSValue> DoGetFontFeatureSettings();
+  already_AddRefed<CSSValue> DoGetFontVariationSettings();
   already_AddRefed<CSSValue> DoGetFontKerning();
   already_AddRefed<CSSValue> DoGetFontLanguageOverride();
   already_AddRefed<CSSValue> DoGetFontSize();
diff --git a/layout/style/nsComputedDOMStylePropertyList.h b/layout/style/nsComputedDOMStylePropertyList.h
index 825976b58..557281810 100644
--- a/layout/style/nsComputedDOMStylePropertyList.h
+++ b/layout/style/nsComputedDOMStylePropertyList.h
@@ -144,6 +144,7 @@ COMPUTED_STYLE_PROP(font_variant_east_asian,       FontVariantEastAsian)
 COMPUTED_STYLE_PROP(font_variant_ligatures,        FontVariantLigatures)
 COMPUTED_STYLE_PROP(font_variant_numeric,          FontVariantNumeric)
 COMPUTED_STYLE_PROP(font_variant_position,         FontVariantPosition)
+COMPUTED_STYLE_PROP(font_variation_settings,       FontVariationSettings)
 COMPUTED_STYLE_PROP(font_weight,                   FontWeight)
 COMPUTED_STYLE_PROP(grid_auto_columns,             GridAutoColumns)
 COMPUTED_STYLE_PROP(grid_auto_flow,                GridAutoFlow)
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index e9f9517e4..b3011b1b1 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -2528,6 +2528,9 @@ pref("layout.css.image-orientation.enabled", true);
 // Is support for the font-display @font-face descriptor enabled?
 pref("layout.css.font-display.enabled", false);
 
+// Enable the font variation stub code?
+pref("layout.css.font-variations.stub", true);
+
 // Are sets of prefixed properties supported?
 pref("layout.css.prefixes.border-image", true);
 pref("layout.css.prefixes.transforms", true);