Remove all the OS X 10.6 SDK forward declarations.

webkit/glue/webmenurunner_mac.mm

Index: webkit/glue/webmenurunner_mac.mm
diff --git a/webkit/glue/webmenurunner_mac.mm b/webkit/glue/webmenurunner_mac.mm
index 7442857c1ff064d480f4ad276595c79a895261ea..fa1abb4cd54b0a35a0645112fba5700a54e5108e 100644
--- a/webkit/glue/webmenurunner_mac.mm
+++ b/webkit/glue/webmenurunner_mac.mm
@@ -6,27 +6,6 @@
 
 #include "base/sys_string_conversions.h"
 
-#if !defined(MAC_OS_X_VERSION_10_6) || \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_6
-enum {
-  NSUserInterfaceLayoutDirectionLeftToRight = 0,
-  NSUserInterfaceLayoutDirectionRightToLeft = 1
-};
-typedef NSInteger NSUserInterfaceLayoutDirection;
-
-@interface NSCell (SnowLeopardSDKDeclarations)
-- (void)setUserInterfaceLayoutDirection:
-    (NSUserInterfaceLayoutDirection)layoutDirection;
-@end
-
-enum {
-  NSTextWritingDirectionEmbedding = (0 << 1),
-  NSTextWritingDirectionOverride = (1 << 1)
-};
-
-static NSString* NSWritingDirectionAttributeName = @"NSWritingDirection";
-#endif
-
 @interface WebMenuRunner (PrivateAPI)
 
 // Worker function used during initialization.