Fix cocos2d#3156 setBlendFunc issue in parser

Author: pandamicro

extensions/cocostudio/loader/parsers/action-2.x.js

@@ -260,7 +260,7 @@
             handle: function(options){
                 var frame = new ccs.BlendFuncFrame();
                 var blendFunc = options["BlendFunc"];
-                if(blendFunc)
+                if(blendFunc && blendFunc["Src"] !== undefined && blendFunc["Dst"] !== undefined)
                     frame.setBlendFunc(new cc.BlendFunc(blendFunc["Src"], blendFunc["Dst"]));
                 return frame;
             }

extensions/cocostudio/loader/parsers/timelineParser-2.x.js

@@ -1292,8 +1292,8 @@
             node.setDebugDrawLength(length);
 
         var blendFunc = json["BlendFunc"];
-        if(blendFunc)
-            node.setBlendFunc(new cc.BlendFunc(blendFunc["Src"] || 0, blendFunc["Dst"] || 0));
+        if(blendFunc && blendFunc["Src"] !== undefined && blendFunc["Dst"] !== undefined)
+            node.setBlendFunc(new cc.BlendFunc(blendFunc["Src"], blendFunc["Dst"]));
 
         parser.generalAttributes(node, json);
         var color = json["CColor"];