dart2js: Fix getter/setter flags in the model.

pkg/compiler/lib/src/js_emitter/program_builder.dart

Index: pkg/compiler/lib/src/js_emitter/program_builder.dart
diff --git a/pkg/compiler/lib/src/js_emitter/program_builder.dart b/pkg/compiler/lib/src/js_emitter/program_builder.dart
index f1144e586093e1be2dfc7a4a83674818ce66dae0..3f75a202c527283a88974e83eb2b88085f1f1768 100644
--- a/pkg/compiler/lib/src/js_emitter/program_builder.dart
+++ b/pkg/compiler/lib/src/js_emitter/program_builder.dart
@@ -388,7 +388,7 @@ class ProgramBuilder {
       bool isIntercepted = backend.fieldHasInterceptedGetter(field);
       if (isIntercepted) {
         getterFlags += 2;
-        if (backend.isInterceptorClass(holder)) {
+        if (!backend.isInterceptorClass(holder)) {
           getterFlags += 1;
         }
       } else {
@@ -401,7 +401,7 @@ class ProgramBuilder {
       bool isIntercepted = backend.fieldHasInterceptedSetter(field);
       if (isIntercepted) {
         setterFlags += 2;
-        if (backend.isInterceptorClass(holder)) {
+        if (!backend.isInterceptorClass(holder)) {
           setterFlags += 1;
         }
       } else {