Cleanup <static_cast>: Switch to toFoo for Accessibility Objects.

Source/core/accessibility/AccessibilityImageMapLink.h

Index: Source/core/accessibility/AccessibilityImageMapLink.h
diff --git a/Source/core/accessibility/AccessibilityImageMapLink.h b/Source/core/accessibility/AccessibilityImageMapLink.h
index 92345dcab1fed428ca9133d466aeaae6a1009176..05941d3e62c5c58580cd9e8691320a8374f3514b 100644
--- a/Source/core/accessibility/AccessibilityImageMapLink.h
+++ b/Source/core/accessibility/AccessibilityImageMapLink.h
@@ -75,6 +75,21 @@ private:
     virtual bool isImageMapLink() const OVERRIDE { return true; }
 };
 
+inline AccessibilityImageMapLink* toAccessibilityImageMapLink(AccessibilityObject* object)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isImageMapLink());
+    return static_cast<AccessibilityImageMapLink*>(object);
+}
+
+inline const AccessibilityImageMapLink* toAccessibilityImageMapLink(const AccessibilityObject* object)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isImageMapLink());
+    return static_cast<const AccessibilityImageMapLink*>(object);
+}
+
+// This will catch anyone doing an unnecessary cast.
+void toAccessibilityImageMapLink(const AccessibilityImageMapLink*);
+
 } // namespace WebCore
 
 #endif // AccessibilityImageMapLink_h