Extract the SVG Filter Reference implementation out of the FilterEffectRenderer into its own type

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 568ec4325ca7a17e61fad7d469a296879bd292b0..f062f1e295d3d4a0d5c002ec39a8ff0d8f40a12d 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -76,6 +76,8 @@
 #include "core/platform/graphics/FloatPoint3D.h"
 #include "core/platform/graphics/FloatRect.h"
 #include "core/platform/graphics/GraphicsContextStateSaver.h"
+#include "core/platform/graphics/filters/ReferenceFilter.h"
+#include "core/platform/graphics/filters/SourceGraphic.h"
 #include "core/platform/graphics/filters/custom/CustomFilterGlobalContext.h"
 #include "core/platform/graphics/filters/custom/CustomFilterOperation.h"
 #include "core/platform/graphics/filters/custom/CustomFilterValidatedProgram.h"
@@ -100,6 +102,7 @@
 #include "core/rendering/RenderScrollbarPart.h"
 #include "core/rendering/RenderTreeAsText.h"
 #include "core/rendering/RenderView.h"
+#include "core/rendering/svg/ReferenceFilterBuilder.h"
 #include "core/rendering/svg/RenderSVGResourceClipper.h"
 #include <wtf/MemoryInstrumentationVector.h>
 #include <wtf/StdLibExtras.h>
@@ -6046,13 +6049,6 @@ void RenderLayer::updateFilters(const RenderStyle* oldStyle, const RenderStyle*
     if (shouldUpdateFilters)
         backing()->updateFilters(renderer()->style());
     updateOrRemoveFilterEffectRenderer();
-    // FIXME: Accelerated SVG reference filters still rely on FilterEffectRenderer to build the filter graph.
-    // Thus, we have to call updateFilters again, after we have a FilterEffectRenderer.
-    // FilterEffectRenderer is intended to render software filters and shouldn't be needed for accelerated filters.
-    // We should extract the SVG graph building functionality out of FilterEffectRenderer, and it should happen in RenderLayer::computeFilterOperations.
-    // https://bugs.webkit.org/show_bug.cgi?id=114051
-    if (shouldUpdateFilters && newStyle->filter().hasReferenceFilter())
-        backing()->updateFilters(renderer()->style());
 }
 
 void RenderLayer::styleChanged(StyleDifference, const RenderStyle* oldStyle)
@@ -6245,6 +6241,22 @@ bool RenderLayer::isCSSCustomFilterEnabled() const
 FilterOperations RenderLayer::computeFilterOperations(const RenderStyle* style)
 {
     const FilterOperations& filters = style->filter();
+    if (filters.hasReferenceFilter()) {
+        for (size_t i = 0; i < filters.size(); ++i) {
+            FilterOperation* filterOperation = filters.operations().at(i).get();
+            if (filterOperation->getOperationType() != FilterOperation::REFERENCE)
+                continue;
+            ReferenceFilterOperation* referenceOperation = static_cast<ReferenceFilterOperation*>(filterOperation);
+            // FIXME: Cache the ReferenceFilter if it didn't change.
+            RefPtr<ReferenceFilter> referenceFilter = ReferenceFilter::create();
+            float zoom = style->effectiveZoom();
+            referenceFilter->setFilterResolution(FloatSize(zoom, zoom));
+            referenceFilter->setLastEffect(ReferenceFilterBuilder::build(referenceFilter.get(), renderer(), referenceFilter->sourceGraphic(),
+                referenceOperation));
+            referenceOperation->setFilter(referenceFilter.release());
+        }
+    }
+
     if (!filters.hasCustomFilter())
         return filters;
 
@@ -6310,14 +6322,7 @@ void RenderLayer::updateOrRemoveFilterEffectRenderer()
         if (RenderLayerFilterInfo* filterInfo = this->filterInfo())
             filterInfo->setRenderer(0);
 
-        // FIXME: Accelerated SVG reference filters shouldn't rely on FilterEffectRenderer to build the filter graph.
-        // https://bugs.webkit.org/show_bug.cgi?id=114051
-
-        // Early-return only if we *don't* have reference filters.
-        // For reference filters, we still want the FilterEffect graph built
-        // for us, even if we're composited.
-        if (!renderer()->style()->filter().hasReferenceFilter())
-            return;
+        return;
     }
     
     RenderLayerFilterInfo* filterInfo = ensureFilterInfo();