Bug 1224013 part 1 - Enable text-emphasis in UA sheets. r=dbaron

The only usage of text-emphasis in UA sheets is to clear it on ruby text. Making
it enabled in UA sheets allows that rule to take effect without additional code
to reload html.css when the pref changes.

--HG--
extra : source : 08e14a9afe4d6ad018c461fd58a48a74aa421759

layout/style/html.css

@@ -818,10 +818,8 @@ rtc, rt {
   font-variant-east-asian: ruby;
 %endif
 }
-@supports (text-emphasis: none) {
-  rtc, rt {
-    text-emphasis: none;
-  }
+rtc, rt {
+  text-emphasis: none;
 }
 rtc:lang(zh), rt:lang(zh) {
   ruby-align: center;

layout/style/nsCSSPropList.h

@@ -3269,14 +3269,16 @@ CSS_PROP_SHORTHAND(
     text-emphasis,
     text_emphasis,
     TextEmphasis,
-    CSS_PROPERTY_PARSE_FUNCTION,
+    CSS_PROPERTY_PARSE_FUNCTION |
+        CSS_PROPERTY_ENABLED_IN_UA_SHEETS,
     "layout.css.text-emphasis.enabled")
 CSS_PROP_TEXT(
     text-emphasis-color,
     text_emphasis_color,
     TextEmphasisColor,
     CSS_PROPERTY_PARSE_VALUE |
-        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED,
+        CSS_PROPERTY_IGNORED_WHEN_COLORS_DISABLED |
+        CSS_PROPERTY_ENABLED_IN_UA_SHEETS,
     "layout.css.text-emphasis.enabled",
     VARIANT_HC,
     nullptr,
@@ -3287,7 +3289,8 @@ CSS_PROP_TEXT(
     text_emphasis_position,
     TextEmphasisPosition,
     CSS_PROPERTY_PARSE_VALUE |
-        CSS_PROPERTY_VALUE_PARSER_FUNCTION,
+        CSS_PROPERTY_VALUE_PARSER_FUNCTION |
+        CSS_PROPERTY_ENABLED_IN_UA_SHEETS,
     "layout.css.text-emphasis.enabled",
     0,
     kTextEmphasisPositionKTable,
@@ -3298,7 +3301,8 @@ CSS_PROP_TEXT(
     text_emphasis_style,
     TextEmphasisStyle,
     CSS_PROPERTY_PARSE_VALUE |
-        CSS_PROPERTY_VALUE_PARSER_FUNCTION,
+        CSS_PROPERTY_VALUE_PARSER_FUNCTION |
+        CSS_PROPERTY_ENABLED_IN_UA_SHEETS,
     "layout.css.text-emphasis.enabled",
     0,
     nullptr,