Update gui to use getter for target costumes

src/containers/costume-tab.jsx

@@ -77,7 +77,7 @@ class CostumeTab extends React.Component {
     }
     handleNewCostume () {
         if (!this.props.vm.editingTarget) return;
-        const costumes = this.props.vm.editingTarget.sprite.costumes || [];
+        const costumes = this.props.vm.editingTarget.getCostumes() || [];
         this.setState({selectedCostumeIndex: Math.max(costumes.length - 1, 0)});
     }
     handleNewBlankCostume () {

src/lib/blocks.js

@@ -36,15 +36,15 @@ export default function (vm) {
     };
 
     const costumesMenu = function () {
-        if (vm.editingTarget && vm.editingTarget.sprite.costumes.length > 0) {
-            return vm.editingTarget.sprite.costumes.map(costume => [costume.name, costume.name]);
+        if (vm.editingTarget && vm.editingTarget.getCostumes().length > 0) {
+            return vm.editingTarget.getCostumes().map(costume => [costume.name, costume.name]);
         }
         return [['', '']];
     };
 
     const backdropsMenu = function () {
-        if (vm.runtime.targets[0] && vm.runtime.targets[0].sprite.costumes.length > 0) {
-            return vm.runtime.targets[0].sprite.costumes.map(costume => [costume.name, costume.name])
+        if (vm.runtime.targets[0] && vm.runtime.targets[0].getCostumes().length > 0) {
+            return vm.runtime.targets[0].getCostumes().map(costume => [costume.name, costume.name])
                 .concat([['next backdrop', 'next backdrop'], ['previous backdrop', 'previous backdrop']]);
         }
         return [['', '']];