Remove the ability in dart2js to turn off syntax-only generic methods.

pkg/compiler/lib/src/serialization/resolved_ast_serialization.dart

Index: pkg/compiler/lib/src/serialization/resolved_ast_serialization.dart
diff --git a/pkg/compiler/lib/src/serialization/resolved_ast_serialization.dart b/pkg/compiler/lib/src/serialization/resolved_ast_serialization.dart
index c3ef3667e9510ff119417bbeccef455ae33e20a7..c839c95adb7eec8e4ce02b3293e608497d642718 100644
--- a/pkg/compiler/lib/src/serialization/resolved_ast_serialization.dart
+++ b/pkg/compiler/lib/src/serialization/resolved_ast_serialization.dart
@@ -400,7 +400,7 @@ class ResolvedAstDeserializer {
               parsing.getScannerOptionsFor(element), reporter, null);
           listener.memberErrors = listener.memberErrors.prepend(false);
           try {
-            Parser parser = new Parser(listener, parsing.parserOptions);
+            Parser parser = new Parser(listener);
             parse(parser);
           } on ParserError catch (e) {
             reporter.internalError(element, '$e');