Implement costume name block

src/blocks/scratch3_looks.js

@@ -252,6 +252,7 @@ class Scratch3LooksBlocks {
             looks_goforwardbackwardlayers: this.goForwardBackwardLayers,
             looks_size: this.getSize,
             looks_costumenumbername: this.getCostumeNumberName,
+            looks_costumename: this.getCostumeName,
             looks_backdropnumbername: this.getBackdropNumberName
         };
     }
@@ -488,6 +489,11 @@ class Scratch3LooksBlocks {
         // Else return name
         return util.target.getCostumes()[util.target.currentCostume].name;
     }
+
+    getCostumeName (args, util) {
+        // Obsolete block from earlier Scratch versions.
+        return util.target.getCostumes()[util.target.currentCostume].name;
+    }
 }
 
 module.exports = Scratch3LooksBlocks;

src/serialization/sb2_specmap.js

@@ -428,6 +428,11 @@ const specMap = {
         argMap: [
         ]
     },
+    'costumeName': {
+        opcode: 'looks_costumename',
+        argMap: [
+        ]
+    },
     'sceneName': {
         opcode: 'looks_backdropnumbername',
         argMap: [