RenderLayer::scrollParent should walk the containing block chain

LayoutTests/compositing/overflow/scroll-parent-absolute-expected.txt

Index: LayoutTests/compositing/overflow/scroll-parent-absolute-expected.txt
diff --git a/LayoutTests/compositing/overflow/scroll-parent-absolute-expected.txt b/LayoutTests/compositing/overflow/scroll-parent-absolute-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..106e477491ff92359d8468fb8f8d1f4362f0dab5
--- /dev/null
+++ b/LayoutTests/compositing/overflow/scroll-parent-absolute-expected.txt
@@ -0,0 +1,75 @@
+(GraphicsLayer
+  (bounds 785.00 5516.00)
+  (children 1
+    (GraphicsLayer
+      (bounds 785.00 5516.00)
+      (contentsOpaque 1)
+      (drawsContent 1)
+      (children 4
+        (GraphicsLayer
+          (position 8.00 8.00)
+          (bounds 500.00 500.00)
+          (contentsOpaque 1)
+          (drawsContent 1)
+          (backgroundColor #0000FF)
+          (children 4
+            (GraphicsLayer
+              (bounds 485.00 485.00)
+              (children 1
+                (GraphicsLayer
+                  (bounds 485.00 5000.00)
+                  (shouldFlattenTransform 0)
+                  (drawsContent 1)
+                  (children 1
+                    (GraphicsLayer
+                    )
+                  )
+                )
+              )
+            )
+            (GraphicsLayer
+              (position 0.00 485.00)
+              (bounds 485.00 15.00)
+              (drawsContent 1)
+            )
+            (GraphicsLayer
+              (position 485.00 0.00)
+              (bounds 15.00 485.00)
+              (drawsContent 1)
+            )
+            (GraphicsLayer
+              (position 485.00 485.00)
+              (bounds 15.00 15.00)
+              (drawsContent 1)
+            )
+          )
+        )
+        (GraphicsLayer
+          (position 8.00 8.00)
+          (bounds 400.00 400.00)
+          (contentsOpaque 1)
+          (drawsContent 1)
+          (backgroundColor #008000)
+          (hasClipParent 1)
+        )
+        (GraphicsLayer
+          (position 8.00 8.00)
+          (bounds 300.00 300.00)
+          (contentsOpaque 1)
+          (drawsContent 1)
+          (backfaceVisibility hidden)
+          (backgroundColor #FFFF00)
+        )
+        (GraphicsLayer
+          (position 8.00 8.00)
+          (bounds 20.00 5000.00)
+          (contentsOpaque 1)
+          (drawsContent 1)
+          (backgroundColor #FA8072)
+          (hasScrollParent 1)
+        )
+      )
+    )
+  )
+)
+