Disable the focus moves to an element which doesn't satisfy the spec.

Source/core/page/FocusController.cpp

Index: Source/core/page/FocusController.cpp
diff --git a/Source/core/page/FocusController.cpp b/Source/core/page/FocusController.cpp
index 149ff8a87bca01cdc267d43e738c6569f5615562..0a18a01eed7edba501cb369e7a1507833649782b 100644
--- a/Source/core/page/FocusController.cpp
+++ b/Source/core/page/FocusController.cpp
@@ -582,9 +582,10 @@ Node* FocusController::nextFocusableNode(FocusNavigationScope scope, Node* start
         }
 
         // First try to find a node with the same tabindex as start that comes after start in the scope.
-        if (Node* winner = findNodeWithExactTabIndex(NodeTraversal::next(*start), tabIndex, FocusTypeForward))
-            return winner;
-
+        if (tabIndex >= 0) {

[hayato, 2014/08/26 07:34:56]

You can use `else` here rather than repeating `if`.


if (tabIndex < 0) {
  ...
} else {
  ...
}

would be better than


if (tabIndex < 0) {
  ...
}
if (tabIndex >= 0) {
  ...
}

+            if (Node* winner = findNodeWithExactTabIndex(NodeTraversal::next(*start), tabIndex, FocusTypeForward))
+                return winner;
+        }
         if (!tabIndex)
             // We've reached the last node in the document with a tabindex of 0. This is the end of the tabbing order.
             return 0;
@@ -628,8 +629,10 @@ Node* FocusController::previousFocusableNode(FocusNavigationScope scope, Node* s
         }
     }
 
-    if (Node* winner = findNodeWithExactTabIndex(startingNode, startingTabIndex, FocusTypeBackward))
-        return winner;
+    if (startingTabIndex >= 0) {

[hayato, 2014/08/26 07:34:56]

Ditto.

+        if (Node* winner = findNodeWithExactTabIndex(startingNode, startingTabIndex, FocusTypeBackward))
+            return winner;
+    }
 
     // There are no nodes before start with the same tabindex as start, so look for a node that:
     // 1) has the highest non-zero tabindex (that is less than start's tabindex), and