update VM for non-droppable extension menu support

package.json

@@ -111,7 +111,7 @@
     "scratch-render": "0.1.0-prerelease.20190605151415",
     "scratch-storage": "1.3.2",
     "scratch-svg-renderer": "0.2.0-prerelease.20190523193400",
-    "scratch-vm": "0.2.0-prerelease.20190618225856",
+    "scratch-vm": "0.2.0-prerelease.20190619042313",
     "selenium-webdriver": "3.6.0",
     "startaudiocontext": "1.2.1",
     "style-loader": "^0.23.0",