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

tests/compiler/dart2js/type_checker_test.dart

Index: tests/compiler/dart2js/type_checker_test.dart
diff --git a/tests/compiler/dart2js/type_checker_test.dart b/tests/compiler/dart2js/type_checker_test.dart
index 0ac90d1221440b8ecb0dca375acc38e66520d28f..96dba28f247bd3a53b571c0563bac197cbd91be1 100644
--- a/tests/compiler/dart2js/type_checker_test.dart
+++ b/tests/compiler/dart2js/type_checker_test.dart
@@ -2724,7 +2724,7 @@ analyze(MockCompiler compiler, String text,
   Token tokens = scan(text);
   NodeListener listener =
       new NodeListener(const ScannerOptions(), compiler.reporter, null);
-  Parser parser = new Parser(listener, new MockParserOptions());
+  Parser parser = new Parser(listener);
   parser.parseStatement(tokens);
   Node node = listener.popNode();
   Element compilationUnit = new CompilationUnitElementX(
@@ -2768,7 +2768,7 @@ analyzeIn(MockCompiler compiler, FunctionElement element, String text,
   Token tokens = scan(text);
   NodeListener listener =
       new NodeListener(const ScannerOptions(), compiler.reporter, null);
-  Parser parser = new Parser(listener, new MockParserOptions(),
+  Parser parser = new Parser(listener,
       asyncAwaitKeywordsEnabled: element.asyncMarker != AsyncMarker.SYNC);
   parser.parseStatement(tokens);
   Node node = listener.popNode();