Bug 1670993 - For webcompat, make -webkit-font-smoothing:antialiased behave like -moz-osx-font-smoothing:grayscale. r=firefox-style-system-reviewers,emilio

Differential Revision: https://phabricator.services.mozilla.com/D212130

dom/base/use_counter_metrics.yaml

@@ -24927,6 +24927,23 @@ use.counter.css.page:
     send_in_pings:
       - use-counters
 
+  css_webkit_font_smoothing:
+    type: counter
+    description: >
+      Whether a page used the CSS property -webkit-font-smoothing.
+      Compare against `use.counter.top_level_content_documents_destroyed`
+      to calculate the rate.
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852098
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852098
+    notification_emails:
+      - dom-core@mozilla.com
+      - emilio@mozilla.com
+    expires: never
+    send_in_pings:
+      - use-counters
+
   css_color_adjust:
     type: counter
     description: >
@@ -26253,23 +26270,6 @@ use.counter.css.page:
     send_in_pings:
       - use-counters
 
-  webkit_font_smoothing:
-    type: counter
-    description: >
-      Whether a page used the (unknown, counted) CSS property -webkit-font-smoothing.
-      Compare against `use.counter.top_level_content_documents_destroyed`
-      to calculate the rate.
-    bugs:
-      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852098
-    data_reviews:
-      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852098
-    notification_emails:
-      - dom-core@mozilla.com
-      - emilio@mozilla.com
-    expires: never
-    send_in_pings:
-      - use-counters
-
   webkit_tap_highlight_color:
     type: counter
     description: >
@@ -36863,6 +36863,23 @@ use.counter.css.doc:
     send_in_pings:
       - use-counters
 
+  css_webkit_font_smoothing:
+    type: counter
+    description: >
+      Whether a document used the CSS property -webkit-font-smoothing.
+      Compare against `use.counter.content_documents_destroyed`
+      to calculate the rate.
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852098
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852098
+    notification_emails:
+      - dom-core@mozilla.com
+      - emilio@mozilla.com
+    expires: never
+    send_in_pings:
+      - use-counters
+
   css_color_adjust:
     type: counter
     description: >
@@ -38189,23 +38206,6 @@ use.counter.css.doc:
     send_in_pings:
       - use-counters
 
-  webkit_font_smoothing:
-    type: counter
-    description: >
-      Whether a document used the (unknown, counted) CSS property -webkit-font-smoothing.
-      Compare against `use.counter.content_documents_destroyed`
-      to calculate the rate.
-    bugs:
-      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852098
-    data_reviews:
-      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852098
-    notification_emails:
-      - dom-core@mozilla.com
-      - emilio@mozilla.com
-    expires: never
-    send_in_pings:
-      - use-counters
-
   webkit_tap_highlight_color:
     type: counter
     description: >
@@ -39956,3 +39956,4 @@ use.counter.css.doc:
     expires: never
     send_in_pings:
       - use-counters
+

gfx/thebes/gfxFontConstants.h

@@ -33,6 +33,9 @@
 
 #define NS_FONT_SMOOTHING_AUTO 0
 #define NS_FONT_SMOOTHING_GRAYSCALE 1
+/* For -webkit-font-smoothing; behaves the same as AUTO, but not aliased for
+   parsing/serialization because that would confuse tests. */
+#define NS_FONT_SMOOTHING_SUBPIXEL_ANTIALIASED 2
 
 #define NS_FONT_KERNING_AUTO 0
 #define NS_FONT_KERNING_NONE 1

layout/style/test/property_database.js

@@ -13082,8 +13082,21 @@ if (IsCSSPropertyPrefEnabled("layout.css.osx-font-smoothing.enabled")) {
     applies_to_cue: true,
     applies_to_marker: true,
     initial_values: ["auto"],
-    other_values: ["grayscale"],
-    invalid_values: ["none", "subpixel-antialiased", "antialiased"],
+    other_values: ["grayscale", "subpixel-antialiased", "antialiased"],
+    invalid_values: ["none"],
+  };
+
+  gCSSProperties["-webkit-font-smoothing"] = {
+    domProp: "webkitFontSmoothing",
+    inherited: true,
+    type: CSS_TYPE_SHORTHAND_AND_LONGHAND,
+    applies_to_first_letter: true,
+    applies_to_first_line: true,
+    applies_to_placeholder: true,
+    applies_to_cue: true,
+    applies_to_marker: true,
+    alias_for: "-moz-osx-font-smoothing",
+    subproperties: ["-moz-osx-font-smoothing"],
   };
 }
 

layout/style/test/test_use_counters.html

@@ -84,7 +84,7 @@ const UNIMPLEMENTED_PROPERTIES = {
       -webkit-background-size: 100px 100px; /* longhand alias */
       transform-origin: top left; /* longhand */
       background: green; /* shorthand */
-      -webkit-font-smoothing: auto; /* counted unknown */
+      -webkit-tap-highlight-color: cyan; /* counted unknown */
     }
   `,
   recorded: [
@@ -92,7 +92,7 @@ const UNIMPLEMENTED_PROPERTIES = {
     "-webkit-background-size",
     "transform-origin",
     "background",
-    "-webkit-font-smoothing",
+    "-webkit-tap-highlight-color",
   ],
   not_recorded: [
     "size",

servo/components/style/properties/counted_unknown_properties.py

@@ -3,7 +3,6 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 COUNTED_UNKNOWN_PROPERTIES = [
-    "-webkit-font-smoothing",
     "-webkit-tap-highlight-color",
     "speak",
     "text-size-adjust",

servo/components/style/properties/longhands/font.mako.rs

@@ -474,11 +474,13 @@ pub mod system_font {
 
 ${helpers.single_keyword(
     "-moz-osx-font-smoothing",
-    "auto grayscale",
+    "auto grayscale subpixel-antialiased",
     engines="gecko",
     gecko_constant_prefix="NS_FONT_SMOOTHING",
     gecko_ffi_name="mFont.smoothing",
     gecko_pref="layout.css.osx-font-smoothing.enabled",
+    aliases="-webkit-font-smoothing:layout.css.osx-font-smoothing.enabled",
+    gecko_aliases="antialiased=grayscale",
     has_effect_on_gecko_scrollbars=False,
     spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/font-smooth)",
     animation_value_type="discrete",