dart2js: remove additionalProperties and store it directly as nativeBlob.

pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart

Index: pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart b/pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart
index 88c5f612ccc7a48d7846d4cbc7267212f3873774..6e5b46d38222b18f527f7e256bb967cbf7f24e35 100644
--- a/pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart
@@ -12,9 +12,7 @@ class ClassEmitter extends CodeEmitterHelper {
   /**
    * Documentation wanted -- johnniwinther
    */
-  void emitClass(Class cls,
-                 ClassBuilder enclosingBuilder,
-                 Map<String, jsAst.Expression> additionalProperties) {
+  void emitClass(Class cls, ClassBuilder enclosingBuilder) {
     ClassElement classElement = cls.element;
 
     assert(invariant(classElement, classElement.isDeclaration));
@@ -43,9 +41,7 @@ class ClassEmitter extends CodeEmitterHelper {
     emitInstanceMembers(cls, builder);
     emitCallStubs(cls, builder);
     emitRuntimeTypeInformation(cls, builder);
-    if (additionalProperties != null) {
-      additionalProperties.forEach(builder.addProperty);
-    }
+    emitNativeInfo(cls, builder);
 
     if (classElement == backend.closureClass) {
       // We add a special getter here to allow for tearing off a closure from
@@ -271,6 +267,12 @@ class ClassEmitter extends CodeEmitterHelper {
     }
   }
 
+  void emitNativeInfo(Class cls, ClassBuilder builder) {
+    if (cls.nativeInfo != null) {
+      builder.addProperty(namer.nativeSpecProperty, js.string(cls.nativeInfo));
+    }
+  }
+
   void emitClassBuilderWithReflectionData(Class cls,
                                           ClassBuilder classBuilder,
                                           ClassBuilder enclosingBuilder) {