Tween compatible instant easing fix

Author: cocojoe

cocos2d-ui/CCBReader/CCAnimationManager.m

@@ -170,6 +170,10 @@ - (CCBSequence*)sequenceFromSequenceId:(int)seqId {
 
 - (CCActionInterval*)actionFromKeyframe0:(CCBKeyframe*)kf0 andKeyframe1:(CCBKeyframe*)kf1 propertyName:(NSString*)name node:(CCNode*)node {
     float duration = kf1.time - kf0.time;
+
+    if(kf0 && kf0.easingType==kCCBKeyframeEasingInstant) {
+        duration = 0;
+    }
 
     if ([name isEqualToString:@"rotation"]) {
         return [CCActionRotateTo actionWithDuration:duration angle:[kf1.value floatValue] simple:YES];