Negate just the IsFixed bit.

third_party/WebKit/Source/core/layout/LayoutView.cpp

Index: third_party/WebKit/Source/core/layout/LayoutView.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutView.cpp b/third_party/WebKit/Source/core/layout/LayoutView.cpp
index 632261ac2556e30c2672fc7851418f87d4541e4f..b03b5eabad9d61e2c88969f99f7f9bd5514a9ffe 100644
--- a/third_party/WebKit/Source/core/layout/LayoutView.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutView.cpp
@@ -406,7 +406,7 @@ void LayoutView::mapAncestorToLocal(const LayoutBoxModelObject* ancestor, Transf
     if (mode & TraverseDocumentBoundaries) {
         if (LayoutPart* parentDocLayoutObject = frame()->ownerLayoutObject()) {
             // A LayoutView is a containing block for fixed-position elements, so don't carry this state across frames.
-            mode &= !IsFixed;
+            mode &= ~IsFixed;
 
             parentDocLayoutObject->mapAncestorToLocal(ancestor, transformState, mode);
             transformState.move(parentDocLayoutObject->contentBoxOffset());