Updating vector should make bitmap resolution 1.

src/virtual-machine.js

@@ -669,6 +669,7 @@ class VirtualMachine extends EventEmitter {
         // so the dataFormat should be 'svg'
         costume.dataFormat = storage.DataFormat.SVG;
         costume.md5 = `${costume.assetId}.${costume.dataFormat}`;
+        costume.bitmapResolution = 1;
         this.emitTargetsUpdate();
     }