Implement will-change-based GPU rasterization hint

Source/core/rendering/style/RenderStyle.cpp

Index: Source/core/rendering/style/RenderStyle.cpp
diff --git a/Source/core/rendering/style/RenderStyle.cpp b/Source/core/rendering/style/RenderStyle.cpp
index f1230077c8fa4ee75a4b250e81a0f95d5ce1a66a..3927e5844d3bcbbd77e8ee06b2c0992e6044a519 100644
--- a/Source/core/rendering/style/RenderStyle.cpp
+++ b/Source/core/rendering/style/RenderStyle.cpp
@@ -651,7 +651,8 @@ StyleDifference RenderStyle::repaintOnlyDiff(const RenderStyle* other, unsigned&
             || rareNonInheritedData->m_perspective != other->rareNonInheritedData->m_perspective
             || rareNonInheritedData->m_perspectiveOriginX != other->rareNonInheritedData->m_perspectiveOriginX
             || rareNonInheritedData->m_perspectiveOriginY != other->rareNonInheritedData->m_perspectiveOriginY
-            || hasWillChangeCompositingHint() != other->hasWillChangeCompositingHint())
+            || hasWillChangeCompositingHint() != other->hasWillChangeCompositingHint()
+            || hasWillChangeGpuRasterizationHint() != other->hasWillChangeGpuRasterizationHint())
             return StyleDifferenceRecompositeLayer;
     }
 
@@ -851,6 +852,25 @@ bool RenderStyle::hasWillChangeCompositingHint() const
     return false;
 }
 
+bool RenderStyle::hasWillChangeGpuRasterizationHint() const
+{
+    if (willChangeContents())
+        return true;
+
+    for (size_t i = 0; i < rareNonInheritedData->m_willChange->m_properties.size(); ++i) {
+        switch (rareNonInheritedData->m_willChange->m_properties[i]) {
+        case CSSPropertyWidth:
+        case CSSPropertyHeight:
+        case CSSPropertyBackgroundColor:
+        case CSSPropertyBackgroundPosition:
+            return true;
+        default:
+            break;
+        }
+    }
+    return false;
+}
+
 inline bool requireTransformOrigin(const Vector<RefPtr<TransformOperation> >& transformOperations, RenderStyle::ApplyTransformOrigin applyOrigin)
 {
     // transform-origin brackets the transform with translate operations.