Backed out changeset a59c7ce8c81e (bug 1957384) for causing reftest failures

dom/base/nsContentUtils.cpp

@@ -1919,6 +1919,33 @@ nsIBidiKeyboard* nsContentUtils::GetBidiKeyboard() {
   return sBidiKeyboard;
 }
 
+/**
+ * This is used to determine whether a character is in one of the classes
+ * which CSS says should be part of the first-letter.  Currently, that is
+ * all punctuation classes (P*).  Note that this is a change from CSS2
+ * which excluded Pc and Pd.
+ *
+ * https://www.w3.org/TR/css-pseudo-4/#first-letter-pseudo
+ * "Punctuation (i.e, characters that belong to the Punctuation (P*) Unicode
+ *  general category [UAX44]) [...]"
+ */
+
+// static
+bool nsContentUtils::IsFirstLetterPunctuation(uint32_t aChar) {
+  switch (mozilla::unicode::GetGeneralCategory(aChar)) {
+    case HB_UNICODE_GENERAL_CATEGORY_CONNECT_PUNCTUATION: /* Pc */
+    case HB_UNICODE_GENERAL_CATEGORY_DASH_PUNCTUATION:    /* Pd */
+    case HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION:   /* Pe */
+    case HB_UNICODE_GENERAL_CATEGORY_FINAL_PUNCTUATION:   /* Pf */
+    case HB_UNICODE_GENERAL_CATEGORY_INITIAL_PUNCTUATION: /* Pi */
+    case HB_UNICODE_GENERAL_CATEGORY_OTHER_PUNCTUATION:   /* Po */
+    case HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION:    /* Ps */
+      return true;
+    default:
+      return false;
+  }
+}
+
 // static
 bool nsContentUtils::IsAlphanumeric(uint32_t aChar) {
   nsUGenCategory cat = mozilla::unicode::GetGenCategory(aChar);