From e3f6690ee7202449b52e57f34d7695923e60a2dd Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Mon, 19 Oct 2020 19:35:03 +0000
Subject: [PATCH] Issue #1671 - Unprefix ::-moz-selection

This actually keeps both pseudo-elements for now, since the prefixed version is
still used internally, but we need the unprefixed version for web compat.
Note: while unprefixing a non-spec-compliant pseudo here, it's exactly in line
with what other browsers do. Nobody is following the spec here and at least
we'll be doing what everyone else is with our unprefixed version.
---
 .../rules/test/browser_rules_pseudo-element_01.js     |  6 +++---
 devtools/shared/css/generated/properties-db.js        |  1 +
 layout/generic/nsTextFrame.cpp                        | 11 +++++++++--
 .../tests/test_getCSSPseudoElementNames.html          |  1 +
 layout/style/nsCSSPseudoElementList.h                 |  3 +++
 5 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/devtools/client/inspector/rules/test/browser_rules_pseudo-element_01.js b/devtools/client/inspector/rules/test/browser_rules_pseudo-element_01.js
index 77b8c06882..72cc7f8980 100644
--- a/devtools/client/inspector/rules/test/browser_rules_pseudo-element_01.js
+++ b/devtools/client/inspector/rules/test/browser_rules_pseudo-element_01.js
@@ -29,7 +29,7 @@ function* testTopLeft(inspector, view) {
       elementRulesNb: 4,
       firstLineRulesNb: 2,
       firstLetterRulesNb: 1,
-      selectionRulesNb: 0,
+      selectionRulesNb: 1,
       afterRulesNb: 1,
       beforeRulesNb: 2
     }
@@ -166,7 +166,7 @@ function* testParagraph(inspector, view) {
       elementRulesNb: 3,
       firstLineRulesNb: 1,
       firstLetterRulesNb: 1,
-      selectionRulesNb: 1,
+      selectionRulesNb: 2,
       beforeRulesNb: 0,
       afterRulesNb: 0
     });
@@ -216,7 +216,7 @@ function* assertPseudoElementRulesNumbers(selector, inspector, view, ruleNbs) {
     firstLetterRules: elementStyle.rules.filter(rule =>
       rule.pseudoElement === ":first-letter"),
     selectionRules: elementStyle.rules.filter(rule =>
-      rule.pseudoElement === ":-moz-selection"),
+      rule.pseudoElement === ":selection"),
     beforeRules: elementStyle.rules.filter(rule =>
       rule.pseudoElement === ":before"),
     afterRules: elementStyle.rules.filter(rule =>
diff --git a/devtools/shared/css/generated/properties-db.js b/devtools/shared/css/generated/properties-db.js
index 316352771a..50d849e79e 100644
--- a/devtools/shared/css/generated/properties-db.js
+++ b/devtools/shared/css/generated/properties-db.js
@@ -9375,6 +9375,7 @@ exports.PSEUDO_ELEMENTS = [
   ":backdrop",
   ":first-letter",
   ":first-line",
+  ":selection",
   ":-moz-selection",
   ":-moz-focus-inner",
   ":-moz-focus-outer",
diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index fcce7f3f65..4decdc8ec9 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -3947,11 +3947,18 @@ nsTextPaintStyle::InitSelectionColorsAndShadow()
   if (selectionElement &&
       selectionStatus == nsISelectionController::SELECTION_ON) {
     RefPtr<nsStyleContext> sc = nullptr;
+    // Probe for both selection and -moz-selection
     sc = mPresContext->StyleSet()->
       ProbePseudoElementStyle(selectionElement,
-                              CSSPseudoElementType::mozSelection,
+                              CSSPseudoElementType::selection,
                               mFrame->StyleContext());
-    // Use -moz-selection pseudo class.
+    if (!sc) {
+      sc = mPresContext->StyleSet()->
+        ProbePseudoElementStyle(selectionElement,
+                                CSSPseudoElementType::mozSelection,
+                                mFrame->StyleContext());
+    }
+    // Use selection pseudo class.
     if (sc) {
       mSelectionBGColor =
         sc->GetVisitedDependentColor(eCSSProperty_background_color);
diff --git a/layout/inspector/tests/test_getCSSPseudoElementNames.html b/layout/inspector/tests/test_getCSSPseudoElementNames.html
index cdb4572d45..8879f21dc4 100644
--- a/layout/inspector/tests/test_getCSSPseudoElementNames.html
+++ b/layout/inspector/tests/test_getCSSPseudoElementNames.html
@@ -16,6 +16,7 @@
     ":first-letter",
     ":first-line",
     ":placeholder",
+    ":selection",
     ":-moz-color-swatch",
     ":-moz-focus-inner",
     ":-moz-focus-outer",
diff --git a/layout/style/nsCSSPseudoElementList.h b/layout/style/nsCSSPseudoElementList.h
index 552c76734a..b8393d3952 100644
--- a/layout/style/nsCSSPseudoElementList.h
+++ b/layout/style/nsCSSPseudoElementList.h
@@ -37,6 +37,9 @@ CSS_PSEUDO_ELEMENT(firstLine, ":first-line",
                    CSS_PSEUDO_ELEMENT_IS_CSS2 |
                    CSS_PSEUDO_ELEMENT_CONTAINS_ELEMENTS)
 
+CSS_PSEUDO_ELEMENT(selection, ":selection",
+                   CSS_PSEUDO_ELEMENT_CONTAINS_ELEMENTS)
+// Keep the prefixed version for now.
 CSS_PSEUDO_ELEMENT(mozSelection, ":-moz-selection",
                    CSS_PSEUDO_ELEMENT_CONTAINS_ELEMENTS)