Do not promote position sticky or fixed elements unless they move with scroll.

third_party/WebKit/Source/core/style/ComputedStyle.h

Index: third_party/WebKit/Source/core/style/ComputedStyle.h
diff --git a/third_party/WebKit/Source/core/style/ComputedStyle.h b/third_party/WebKit/Source/core/style/ComputedStyle.h
index 3903fb774a52eae5b7987215073a7a4908b0e2e6..dce07220897ecd437d7dc0d2cb894ded7e0b006a 100644
--- a/third_party/WebKit/Source/core/style/ComputedStyle.h
+++ b/third_party/WebKit/Source/core/style/ComputedStyle.h
@@ -3194,7 +3194,12 @@ class CORE_EXPORT ComputedStyle : public ComputedStyleBase,
            position() == EPosition::kSticky;
   }
   bool hasViewportConstrainedPosition() const {
-    return position() == EPosition::kFixed || position() == EPosition::kSticky;
+    return position() == EPosition::kFixed;
+  }
+  bool hasStickyConstrainedPosition() const {
+    return position() == EPosition::kSticky &&
+           (!top().isAuto() || !left().isAuto() || !right().isAuto() ||
+            !bottom().isAuto());
   }
 
   // Clip utility functions.