Support background images on ::first-line

https://bugs.webkit.org/show_bug.cgi?id=244039
<rdar://98157640>

Reviewed by Simon Fraser.

This sort-of-worked (no paint invalidation) and got completely broken in 248098@main refactoring
because we don't even trigger the resource load.

This patch fixes the regression and also adds paint invalidation.

* LayoutTests/TestExpectations:
* Source/WebCore/rendering/RenderBox.cpp:

Issue a repaint for ::first-line style if needed.

(WebCore::RenderBox::imageChanged):
* Source/WebCore/rendering/RenderElement.cpp:
(WebCore::RenderElement::styleDidChange):

Register renderer as client for resources in ::first-line style.

(WebCore::RenderElement::willBeDestroyed):

Unregister.

* Source/WebCore/style/StylePendingResources.cpp:
(WebCore::Style::loadPendingResources):

Trigger the load for resources in ::first-line style.

Canonical link: https://commits.webkit.org/253553@main

LayoutTests/TestExpectations

@@ -1799,7 +1799,6 @@ webkit.org/b/186045 imported/w3c/web-platform-tests/css/css-backgrounds/backgrou
 webkit.org/b/186045 imported/w3c/web-platform-tests/css/css-backgrounds/background-clip-color-repaint.html [ Skip ]
 webkit.org/b/186045 imported/w3c/web-platform-tests/css/css-backgrounds/background-color-body-propagation-006.html [ Skip ]
 webkit.org/b/186045 imported/w3c/web-platform-tests/css/css-backgrounds/background-color-root-propagation-002.html [ Skip ]
-webkit.org/b/186045 imported/w3c/web-platform-tests/css/css-backgrounds/background-image-first-line.html [ Skip ]
 webkit.org/b/186045 imported/w3c/web-platform-tests/css/css-backgrounds/background-image-none-gradient-repaint.html [ Skip ]
 webkit.org/b/186045 imported/w3c/web-platform-tests/css/css-backgrounds/border-radius-dynamic-from-no-radius.html [ Skip ]
 webkit.org/b/186045 imported/w3c/web-platform-tests/css/css-backgrounds/child-move-reveals-parent-background.html [ Skip ]

Source/WebCore/rendering/RenderBox.cpp

@@ -2049,9 +2049,19 @@ void RenderBox::imageChanged(WrappedImagePtr image, const IntRect*)
         markShapeOutsideDependentsForLayout();
     }
 
-    bool didFullRepaint = repaintLayerRectsForImage(image, style().backgroundLayers(), true);
-    if (!didFullRepaint)
-        repaintLayerRectsForImage(image, style().maskLayers(), false);
+    bool didFullRepaint = false;
+
+    auto repaintForBackgroundAndMask = [&](auto& style) {
+        if (!didFullRepaint)
+            didFullRepaint = repaintLayerRectsForImage(image, style.backgroundLayers(), true);
+        if (!didFullRepaint)
+            didFullRepaint = repaintLayerRectsForImage(image, style.maskLayers(), false);
+    };
+
+    repaintForBackgroundAndMask(style());
+
+    if (auto* firstLineStyle = style().getCachedPseudoStyle(PseudoId::FirstLine))
+        repaintForBackgroundAndMask(*firstLineStyle);
 
     if (!isComposited())
         return;

Source/WebCore/rendering/RenderElement.cpp

@@ -882,11 +882,19 @@ static inline bool areCursorsEqual(const RenderStyle* a, const RenderStyle* b)
 
 void RenderElement::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
 {
-    updateFillImages(oldStyle ? &oldStyle->backgroundLayers() : nullptr, m_style.backgroundLayers());
-    updateFillImages(oldStyle ? &oldStyle->maskLayers() : nullptr, m_style.maskLayers());
-    updateImage(oldStyle ? oldStyle->borderImage().image() : nullptr, m_style.borderImage().image());
-    updateImage(oldStyle ? oldStyle->maskBoxImage().image() : nullptr, m_style.maskBoxImage().image());
-    updateShapeImage(oldStyle ? oldStyle->shapeOutside() : nullptr, m_style.shapeOutside());
+    auto registerImages = [this](auto& style, auto* oldStyle) {
+        updateFillImages(oldStyle ? &oldStyle->backgroundLayers() : nullptr, style.backgroundLayers());
+        updateFillImages(oldStyle ? &oldStyle->maskLayers() : nullptr, style.maskLayers());
+        updateImage(oldStyle ? oldStyle->borderImage().image() : nullptr, style.borderImage().image());
+        updateImage(oldStyle ? oldStyle->maskBoxImage().image() : nullptr, style.maskBoxImage().image());
+        updateShapeImage(oldStyle ? oldStyle->shapeOutside() : nullptr, style.shapeOutside());
+    };
+
+    registerImages(style(), oldStyle);
+
+    // Are there other pseudo-elements that need the resources to be registered?
+    if (auto* firstLineStyle = style().getCachedPseudoStyle(PseudoId::FirstLine))
+        registerImages(*firstLineStyle, oldStyle ? oldStyle->getCachedPseudoStyle(PseudoId::FirstLine) : nullptr);
 
     SVGRenderSupport::styleChanged(*this, oldStyle);
 
@@ -1012,24 +1020,29 @@ void RenderElement::willBeDestroyed()
 
     clearSubtreeLayoutRootIfNeeded();
 
+    auto unregisterImage = [this](auto* image) {
+        if (image)
+            image->removeClient(*this);
+    };
+
+    auto unregisterImages = [&](auto& style) {
+        for (auto* backgroundLayer = &style.backgroundLayers(); backgroundLayer; backgroundLayer = backgroundLayer->next())
+            unregisterImage(backgroundLayer->image());
+        for (auto* maskLayer = &style.maskLayers(); maskLayer; maskLayer = maskLayer->next())
+            unregisterImage(maskLayer->image());
+        unregisterImage(style.borderImage().image());
+        unregisterImage(style.maskBoxImage().image());
+        if (auto shapeValue = style.shapeOutside())
+            unregisterImage(shapeValue->image());
+    };
+
     if (hasInitializedStyle()) {
-        for (auto* bgLayer = &m_style.backgroundLayers(); bgLayer; bgLayer = bgLayer->next()) {
-            if (auto* backgroundImage = bgLayer->image())
-                backgroundImage->removeClient(*this);
-        }
-        for (auto* maskLayer = &m_style.maskLayers(); maskLayer; maskLayer = maskLayer->next()) {
-            if (auto* maskImage = maskLayer->image())
-                maskImage->removeClient(*this);
-        }
-        if (auto* borderImage = m_style.borderImage().image())
-            borderImage->removeClient(*this);
-        if (auto* maskBoxImage = m_style.maskBoxImage().image())
-            maskBoxImage->removeClient(*this);
-        if (auto shapeValue = m_style.shapeOutside()) {
-            if (auto shapeImage = shapeValue->image())
-                shapeImage->removeClient(*this);
-        }
+        unregisterImages(m_style);
+
+        if (auto* firstLineStyle = style().getCachedPseudoStyle(PseudoId::FirstLine))
+            unregisterImages(*firstLineStyle);
     }
+
     if (m_hasPausedImageAnimations)
         view().removeRendererWithPausedImageAnimations(*this);
 }

Source/WebCore/style/StylePendingResources.cpp

@@ -103,6 +103,10 @@ void loadPendingResources(RenderStyle& style, Document& document, const Element*
 
     if (style.shapeOutside())
         loadPendingImage(document, style.shapeOutside()->image(), element, LoadPolicy::Anonymous);
+
+    // Are there other pseudo-elements that need resource loading? 
+    if (auto* firstLineStyle = style.getCachedPseudoStyle(PseudoId::FirstLine))
+        loadPendingResources(*firstLineStyle, document, element);
 }
 
 }