Fix some minor typos related to the word "accessibility".

content/browser/accessibility/browser_accessibility_cocoa.mm

Index: content/browser/accessibility/browser_accessibility_cocoa.mm
diff --git a/content/browser/accessibility/browser_accessibility_cocoa.mm b/content/browser/accessibility/browser_accessibility_cocoa.mm
index 85805688499cbd5325740136d76023fbbba2569a..f433db3fceeb5b8d701b2b0f7e4d119a46e30783 100644
--- a/content/browser/accessibility/browser_accessibility_cocoa.mm
+++ b/content/browser/accessibility/browser_accessibility_cocoa.mm
@@ -1361,7 +1361,7 @@ NSDictionary* attributeToMethodNameMap = nil;
   return NO;
 }
 
-// Returns whether or not this object should be ignored in the accessibilty
+// Returns whether or not this object should be ignored in the accessibility
 // tree.
 - (BOOL)accessibilityIsIgnored {
   if (!browserAccessibility_)
@@ -1370,7 +1370,7 @@ NSDictionary* attributeToMethodNameMap = nil;
   return [self isIgnored];
 }
 
-// Performs the given accessibilty action on the webkit accessibility object
+// Performs the given accessibility action on the webkit accessibility object
 // that backs this object.
 - (void)accessibilityPerformAction:(NSString*)action {
   if (!browserAccessibility_)