Simplify subtree (now subsequence) caching

Source/platform/graphics/paint/SubtreeDisplayItem.h

Index: Source/platform/graphics/paint/SubtreeDisplayItem.h
diff --git a/Source/platform/graphics/paint/SubtreeDisplayItem.h b/Source/platform/graphics/paint/SubtreeDisplayItem.h
index 67e87db149033fb284fa728d1f816fb2c94b032c..3f7445f054381055513c96a4bde6088869d8c152 100644
--- a/Source/platform/graphics/paint/SubtreeDisplayItem.h
+++ b/Source/platform/graphics/paint/SubtreeDisplayItem.h
@@ -13,23 +13,19 @@ namespace blink {
 
 class BeginSubtreeDisplayItem final : public PairedBeginDisplayItem {
 public:
-    BeginSubtreeDisplayItem(const DisplayItemClientWrapper& client, Type type)
-        : PairedBeginDisplayItem(client, type, sizeof(*this))
-    {
-        ASSERT(isBeginSubtreeType(type));
-    }
+    BeginSubtreeDisplayItem(const DisplayItemClientWrapper& client)
+        : PairedBeginDisplayItem(client, BeginSubtree, sizeof(*this))
+    { }
 };
 
 class EndSubtreeDisplayItem final : public PairedEndDisplayItem {
 public:
-    EndSubtreeDisplayItem(const DisplayItemClientWrapper& client, Type type)
-        : PairedEndDisplayItem(client, type, sizeof(*this))
-    {
-        ASSERT(isEndSubtreeType(type));
-    }
+    EndSubtreeDisplayItem(const DisplayItemClientWrapper& client)
+        : PairedEndDisplayItem(client, EndSubtree, sizeof(*this))
+    { }
 
 #if ENABLE(ASSERT)
-    bool isEndAndPairedWith(DisplayItem::Type otherType) const final { return DisplayItem::isBeginSubtreeType(otherType); }
+    bool isEndAndPairedWith(DisplayItem::Type otherType) const final { return otherType == BeginSubtree; }
 #endif
 };