Introduce "navigation target classification" for spatial navigation

Source/core/page/SpatialNavigation.cpp

Index: Source/core/page/SpatialNavigation.cpp
diff --git a/Source/core/page/SpatialNavigation.cpp b/Source/core/page/SpatialNavigation.cpp
index e9ea56911a233c090ba660d29a03419265d2e80c..1b4167f9557b5a6d0139fb838ecadfc765f29332 100644
--- a/Source/core/page/SpatialNavigation.cpp
+++ b/Source/core/page/SpatialNavigation.cpp
@@ -54,7 +54,7 @@ static void deflateIfOverlapped(LayoutRect&, LayoutRect&);
 static LayoutRect rectToAbsoluteCoordinates(LocalFrame* initialFrame, const LayoutRect&);
 static bool isScrollableNode(const Node*);
 
-FocusCandidate::FocusCandidate(Node* node, FocusType type)
+FocusCandidate::FocusCandidate(Node* node, FocusType type, NavigationClass targetClass)
     : visibleNode(nullptr)
     , focusableNode(nullptr)
     , enclosingScrollableBox(nullptr)
@@ -62,6 +62,7 @@ FocusCandidate::FocusCandidate(Node* node, FocusType type)
     , alignment(None)
     , isOffscreen(true)
     , isOffscreenAfterScrolling(true)
+    , targetClass(targetClass)
 {
     ASSERT(node);
     ASSERT(node->isElementNode());