Generate constants in server as we do in plugin

pkg/analysis_server/tool/spec/generate_all.dart

Index: pkg/analysis_server/tool/spec/generate_all.dart
diff --git a/pkg/analysis_server/tool/spec/generate_all.dart b/pkg/analysis_server/tool/spec/generate_all.dart
index 4e3bc71e447ff9682ccd9ada78f244592609d9ce..58a4634355c8ebc34dc89b4e45b1091a6a6c6df7 100644
--- a/pkg/analysis_server/tool/spec/generate_all.dart
+++ b/pkg/analysis_server/tool/spec/generate_all.dart
@@ -12,6 +12,7 @@ import 'codegen_dart_protocol.dart' as codegen_dart_protocol;
 import 'codegen_inttest_methods.dart' as codegen_inttest_methods;
 import 'codegen_java_types.dart' as codegen_java_types;
 import 'codegen_matchers.dart' as codegen_matchers;
+import 'codegen_protocol_constants.dart' as codegen_protocol_constants;
 import 'to_html.dart' as to_html;
 
 /**
@@ -33,6 +34,7 @@ List<GeneratedContent> get allTargets {
   targets.add(codegen_java_types.targetDir);
   targets.add(codegen_inttest_methods.target);
   targets.add(codegen_matchers.target);
+  targets.add(codegen_protocol_constants.target);
   targets.add(to_html.target);
   return targets;
 }