dart2js: Implement frequency based naming.

pkg/compiler/lib/src/dart2js.dart

Index: pkg/compiler/lib/src/dart2js.dart
diff --git a/pkg/compiler/lib/src/dart2js.dart b/pkg/compiler/lib/src/dart2js.dart
index 3b351afdd8fb41fa0892832759d9fd4251853dc1..2cbaf313fa8596f24c025d1bd7cda2c89e7a8529 100644
--- a/pkg/compiler/lib/src/dart2js.dart
+++ b/pkg/compiler/lib/src/dart2js.dart
@@ -311,6 +311,7 @@ Future<api.CompilationResult> compile(List<String> argv) {
         '--output-type=dart|--output-type=dart-multi|--output-type=js',
         setOutputType),
     new OptionHandler('--use-cps-ir', passThrough),
+    new OptionHandler('--no-frequency-based-minification', passThrough),
     new OptionHandler('--verbose', setVerbose),
     new OptionHandler('--version', (_) => wantVersion = true),
     new OptionHandler('--library-root=.+', setLibraryRoot),
@@ -648,6 +649,10 @@ be removed in a future version:
 
   --use-cps-ir
     Experimental.  Use the new CPS based backend for code generation.
+
+  --no-frequency-based-minification
+    Experimental.  Disabled the new frequency based minifying namer and use the
+    old namer instead.
 '''.trim());
 }