Update worker mode to use the bazel protos directly instead of json

pkg/analyzer_cli/lib/src/options.dart

Index: pkg/analyzer_cli/lib/src/options.dart
diff --git a/pkg/analyzer_cli/lib/src/options.dart b/pkg/analyzer_cli/lib/src/options.dart
index 2c543fa99a5b599d17bdaee0865e3c4ad505b032..a8fec7965abec4bf7ab191b19d0b34a273e2d964 100644
--- a/pkg/analyzer_cli/lib/src/options.dart
+++ b/pkg/analyzer_cli/lib/src/options.dart
@@ -263,6 +263,12 @@ class CommandLineOptions {
   }
 
   static CommandLineOptions _parse(List<String> args) {
+    // Check if the args are in a file (bazel worker mode).
+    if (args.last.startsWith('@')) {
+      var argsFile = new File(args.last.substring(1));
+      args = argsFile.readAsLinesSync();
+    }
+
     args = args.expand((String arg) => arg.split('=')).toList();
     var parser = new CommandLineParser()
       ..addFlag('batch',