Copy snapshot file into assets (#12523)

packages/flutter_tools/gradle/flutter.gradle

@@ -393,6 +393,7 @@ class FlutterTask extends BaseFlutterTask {
     CopySpec getAssets() {
         return project.copySpec {
 	     from "${intermediateDir}/app.flx"
+	     from "${intermediateDir}/snapshot_blob.bin"
             if (buildMode != 'debug') {
                 from "${intermediateDir}/vm_snapshot_data"
                 from "${intermediateDir}/vm_snapshot_instr"