Check if drawFocusRingMaskWithFrame:inView: exists when drawing focus ring

Source/platform/mac/WebCoreNSCellExtras.mm

Index: Source/platform/mac/WebCoreNSCellExtras.mm
diff --git a/Source/platform/mac/WebCoreNSCellExtras.mm b/Source/platform/mac/WebCoreNSCellExtras.mm
index 1b4f2f37c3b4cf6e743edad382165980992522d5..959f0fd741a15cb9271be6a8c47a815f56db5cb1 100644
--- a/Source/platform/mac/WebCoreNSCellExtras.mm
+++ b/Source/platform/mac/WebCoreNSCellExtras.mm
@@ -25,12 +25,13 @@
 
 #import "platform/mac/WebCoreNSCellExtras.h"
 
-#if !BUTTON_CELL_DRAW_WITH_FRAME_DRAWS_FOCUS_RING
-
 @implementation NSCell (WebCoreFocusRingDrawing)
 
 - (void)_web_drawFocusRingWithFrame:(NSRect)cellFrame inView:(NSView *)controlView
 {
+    // FIXME: Remove this check when we drop support for Mac OS X 10.6
+    if (![self respondsToSelector:@selector(drawFocusRingMaskWithFrame:inView:)])
+        return;
     CGContextRef cgContext = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
     CGContextSaveGState(cgContext);
     NSSetFocusRingStyle(NSFocusRingOnly);
@@ -41,5 +42,3 @@
 }
 
 @end
-
-#endif // !BUTTON_CELL_DRAW_WITH_FRAME_DRAWS_FOCUS_RING