Move computation of method flags into model.

pkg/compiler/lib/src/use_unused_api.dart

Index: pkg/compiler/lib/src/use_unused_api.dart
diff --git a/pkg/compiler/lib/src/use_unused_api.dart b/pkg/compiler/lib/src/use_unused_api.dart
index 2713e0df0f3f931676b57cd2a0de4639e5917e44..b9870853746efedc8579582383560379325b6ff4 100644
--- a/pkg/compiler/lib/src/use_unused_api.dart
+++ b/pkg/compiler/lib/src/use_unused_api.dart
@@ -26,6 +26,7 @@ import 'inferrer/type_graph_inferrer.dart' as type_graph_inferrer;
 import 'io/code_output.dart' as io;
 import 'js/js.dart' as js;
 import 'js_emitter/js_emitter.dart' as js_emitter;
+import 'js_emitter/program_builder.dart' as program_builder;
 import 'source_file_provider.dart' as source_file_provider;
 import 'ssa/ssa.dart' as ssa;
 import 'tree/tree.dart' as tree;
@@ -65,6 +66,7 @@ void main(List<String> arguments) {
   useTypes();
   useCodeEmitterTask(null);
   useScript(null);
+  useProgramBuilder(null);
 }
 
 useApi() {
@@ -274,3 +276,8 @@ useCodeEmitterTask(js_emitter.CodeEmitterTask codeEmitterTask) {
 useScript(dart2jslib.Script script) {
   script.copyWithFile(null);
 }
+
+useProgramBuilder(program_builder.ProgramBuilder builder) {
+  builder.buildMethodHackForIncrementalCompilation(null);
+  builder.buildClassWithFieldsForTry(null);
+}