Provide option to suppress mirrors metadata

lib/src/compiler/code_generator.dart

Index: lib/src/compiler/code_generator.dart
diff --git a/lib/src/compiler/code_generator.dart b/lib/src/compiler/code_generator.dart
index 8eea4be80d5297944d1d943d89ab9ad7a31a2008..4907417242f0031878e62dc7046daaa031ba3636 100644
--- a/lib/src/compiler/code_generator.dart
+++ b/lib/src/compiler/code_generator.dart
@@ -1148,9 +1148,8 @@ class CodeGenerator extends GeneralizingAstVisitor
 
   void _emitClassMetadata(List<Annotation> metadata, JS.Expression className,
       List<JS.Statement> body) {
-    // TODO(vsm): Make this optional per #268.
     // Metadata
-    if (metadata.isNotEmpty) {
+    if (options.emitMetadata && metadata.isNotEmpty) {
       body.add(js.statement('#[dart.metadata] = () => #;', [
         className,
         new JS.ArrayInitializer(
@@ -2222,8 +2221,7 @@ class CodeGenerator extends GeneralizingAstVisitor
           parameters != null ? _parameterMetadata(parameters[i]) : [];
       var typeName = _emitType(types[i]);
       var value = typeName;
-      // TODO(vsm): Make this optional per #268.
-      if (metadata.isNotEmpty) {
+      if (options.emitMetadata && metadata.isNotEmpty) {
         metadata = metadata.map(_instantiateAnnotation).toList();
         value = new JS.ArrayInitializer([typeName]..addAll(metadata));
       }