dart2js: minify 'static:' tag

pkg/compiler/lib/src/js_backend/frequency_namer.dart

Index: pkg/compiler/lib/src/js_backend/frequency_namer.dart
diff --git a/pkg/compiler/lib/src/js_backend/frequency_namer.dart b/pkg/compiler/lib/src/js_backend/frequency_namer.dart
index 6fa2ccf8ec9e6b513baf7007a15cfdd016f94341..fa3b79bc7b14135ded0d03ed26be129410554929 100644
--- a/pkg/compiler/lib/src/js_backend/frequency_namer.dart
+++ b/pkg/compiler/lib/src/js_backend/frequency_namer.dart
@@ -21,6 +21,9 @@ class FrequencyBasedNamer extends Namer with _MinifiedFieldNamer,
   final String setterPrefix = 's';
   final String callPrefix = ''; // this will create function names $<n>
 
+  jsAst.Name get staticsPropertyName =>
+      _staticsPropertyName ??= getFreshName(instanceScope, 'static');
+
   FrequencyBasedNamer(Compiler compiler) : super(compiler) {
     fieldRegistry = new _FieldNamingRegistry(this);
   }