Layer squashing causes incorrect rendering while scrolling in Gmail

LayoutTests/compositing/squashing/composited-bounds-for-negative-z-expected.txt

Index: LayoutTests/compositing/squashing/composited-bounds-for-negative-z-expected.txt
diff --git a/LayoutTests/compositing/squashing/composited-bounds-for-negative-z-expected.txt b/LayoutTests/compositing/squashing/composited-bounds-for-negative-z-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..cd5095a4b6520315870705574f07a90c1b751527
--- /dev/null
+++ b/LayoutTests/compositing/squashing/composited-bounds-for-negative-z-expected.txt
@@ -0,0 +1,61 @@
+(GraphicsLayer
+  (bounds 800.00 600.00)
+  (children 1
+    (GraphicsLayer
+      (bounds 800.00 600.00)
+      (contentsOpaque 1)
+      (children 1
+        (GraphicsLayer
+          (bounds 800.00 408.00)
+          (drawsContent 1)
+          (children 4
+            (GraphicsLayer
+              (position 8.00 100.00)
+              (bounds 10.00 10.00)
+              (contentsOpaque 1)
+              (drawsContent 1)
+              (backgroundColor #FF0000)
+            )
+            (GraphicsLayer
+              (bounds 800.00 408.00)
+              (drawsContent 1)
+            )
+            (GraphicsLayer
+              (position 108.00 100.00)
+              (bounds 300.00 300.00)
+              (children 2
+                (GraphicsLayer
+                  (bounds 285.00 300.00)
+                  (children 1
+                    (GraphicsLayer
+                      (bounds 285.00 1000.00)
+                      (shouldFlattenTransform 0)
+                    )
+                  )
+                )
+                (GraphicsLayer
+                  (position 285.00 0.00)
+                  (bounds 15.00 300.00)
+                )
+              )
+            )
+            (GraphicsLayer
+              (children 2
+                (GraphicsLayer
+                  (position 108.00 100.00)
+                  (bounds 285.00 1000.00)
+                )
+                (GraphicsLayer
+                  (position 108.00 100.00)
+                  (bounds 285.00 1000.00)
+                  (drawsContent 1)
+                )
+              )
+            )
+          )
+        )
+      )
+    )
+  )
+)
+