[ios] Removed -[CRWSessionController goDelta:].

ios/web/navigation/crw_session_controller.mm

Index: ios/web/navigation/crw_session_controller.mm
diff --git a/ios/web/navigation/crw_session_controller.mm b/ios/web/navigation/crw_session_controller.mm
index c16fe5a26cff1e853fa2751f99b1dd3d5e8b4d84..afd334620389f81c412ca7840f4947226eb0baa0 100644
--- a/ios/web/navigation/crw_session_controller.mm
+++ b/ios/web/navigation/crw_session_controller.mm
@@ -599,11 +599,6 @@ NSString* const kWindowNameKey = @"windowName";
   DCHECK(_pendingEntryIndex == -1 || _pendingEntry);
 }
 
-- (BOOL)canGoDelta:(int)delta {
-  NSInteger index = [self indexOfEntryForDelta:delta];
-  return 0 <= index && static_cast<NSUInteger>(index) < _entries.count;
-}
-
 - (void)goToEntryAtIndex:(NSInteger)index {
   if (index < 0 || static_cast<NSUInteger>(index) >= _entries.count)
     return;