Disallow tabsToLinks setting to prevent tabbing to anchor with tabIndex.

Source/core/html/HTMLAnchorElement.cpp

Index: Source/core/html/HTMLAnchorElement.cpp
diff --git a/Source/core/html/HTMLAnchorElement.cpp b/Source/core/html/HTMLAnchorElement.cpp
index 6e688ce98c887adc5fcced2ccfed385ffbc58a0f..200abfe38f5f357c8797b014c1058256a813d7f5 100644
--- a/Source/core/html/HTMLAnchorElement.cpp
+++ b/Source/core/html/HTMLAnchorElement.cpp
@@ -163,12 +163,14 @@ bool HTMLAnchorElement::isMouseFocusable() const
 
 bool HTMLAnchorElement::isKeyboardFocusable() const
 {
-    if (!isLink())
-        return HTMLElement::isKeyboardFocusable();
-
     if (!isFocusable())
         return false;
 
+    // If the tab index is set explicitly, ignore the tabsToLinks
+    // setting and empty bounding box check.
+    if (Element::supportsFocus())
+        return HTMLElement::isKeyboardFocusable();
+
     Page* page = document().page();
     if (!page)
         return false;