remove remaining references to sky_snapshot (#8665)

packages/flutter_tools/lib/src/cache.dart

@@ -366,7 +366,7 @@ class FlutterEngine {
     for (FileSystemEntity entity in dir.listSync()) {
       if (entity is File) {
         final String name = fs.path.basename(entity.path);
-        if (name == 'sky_snapshot' || name == 'sky_shell')
+        if (name == 'sky_shell')
           os.makeExecutable(entity);
       }
     }

packages/flutter_tools/lib/src/commands/run.dart

@@ -99,9 +99,6 @@ class RunCommand extends RunCommandBase {
         help: 'Path to a pre-built kernel blob to use when running.\n'
               'This option only exists for testing new kernel code execution on devices\n'
               'and is not needed during normal application development.');
-    argParser.addOption('snapshotter',
-        hide: !verboseHelp,
-        help: 'Specify the path to the sky_snapshot binary.');
     argParser.addOption('packages',
         hide: !verboseHelp,
         help: 'Specify the path to the .packages file.');