dart2js: Don't assume fields are needed, if they are static.

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 d593fae74e1b6c85f9cd16475555ec19707e1f3f..98a9902c75e049b4a350067ff2ffb50296d53666 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
@@ -125,7 +125,8 @@ class ClassEmitter extends CodeEmitterHelper {
         // generate the constructor.  For native classes there are no
         // constructors, so we don't need the fields unless we are generating
         // accessors at runtime.
-        if (!classIsNative || needsAccessor) {
+        bool needsFieldsForConstructor = !emitStatics && !classIsNative;
+        if (needsFieldsForConstructor || needsAccessor) {
           var metadata = emitter.metadataEmitter.buildMetadataFunction(field);
           if (metadata != null) {
             hasMetadata = true;