Implement will-change-based GPU rasterization hint

Source/core/rendering/compositing/CompositedLayerMapping.cpp

Index: Source/core/rendering/compositing/CompositedLayerMapping.cpp
diff --git a/Source/core/rendering/compositing/CompositedLayerMapping.cpp b/Source/core/rendering/compositing/CompositedLayerMapping.cpp
index 61400f073658a38f28ee5777bf143b0b5ad1ec8d..9cd437e9389614bf28805c5f3da160eabf37e9b6 100644
--- a/Source/core/rendering/compositing/CompositedLayerMapping.cpp
+++ b/Source/core/rendering/compositing/CompositedLayerMapping.cpp
@@ -216,6 +216,7 @@ void CompositedLayerMapping::createPrimaryGraphicsLayer()
     updateOpacity(renderer()->style());
     updateTransform(renderer()->style());
     updateFilters(renderer()->style());
+    updateHasGpuRasterizationHint(renderer()->style());
 
     if (RuntimeEnabledFeatures::cssCompositingEnabled()) {
         updateLayerBlendMode(renderer()->style());
@@ -293,6 +294,11 @@ void CompositedLayerMapping::updateIsRootForIsolatedGroup()
     m_graphicsLayer->setIsRootForIsolatedGroup(isolate);
 }
 
+void CompositedLayerMapping::updateHasGpuRasterizationHint(const RenderStyle* style)
+{
+    m_graphicsLayer->setHasGpuRasterizationHint(style->hasWillChangeGpuRasterizationHint());
+}
+
 void CompositedLayerMapping::updateContentsOpaque()
 {
     // For non-root layers, background is always painted by the primary graphics layer.
@@ -852,6 +858,7 @@ GraphicsLayerUpdater::UpdateType CompositedLayerMapping::updateGraphicsLayerGeom
         updateIsRootForIsolatedGroup();
     }
 
+    updateHasGpuRasterizationHint(renderer()->style());
     updateContentsRect();
     updateBackgroundColor();
     updateDrawsContent();