Clean up unused spec

Author: helin24

tool/plugin/lib/plugin.dart

@@ -509,8 +509,6 @@ class GenerateCommand extends ProductCommand {
 
   @override
   Future<int> doit() async {
-    var json = readProductMatrix();
-    var spec = SyntheticBuildSpec.fromJson(json.first, release, specs);
     if (!genPresubmitYaml(specs)) {
       return 1;
     }

tool/plugin/test/plugin_test.dart

@@ -182,7 +182,6 @@ void main() {
       await runner.run(["-d../..", "make"]).whenComplete(() {
         cmd = (runner.commands['make'] as TestMakeCommand);
       });
-      var spec = cmd.specs[0];
       await removeAll('../../build/classes');
       var file = File("../../build/classes/META-INF/plugin.xml");
       expect(file.existsSync(), isTrue);