dart2js: Implement frequency based naming.

pkg/compiler/lib/src/dart2js.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.cmdline;
 
 import 'dart:async'
     show Future, EventSink;
 import 'dart:convert' show UTF8, LineSplitter;
 import 'dart:io'
@@ skipping 293 matching lines @@
       diagnosticHandler.showWarnings = false;
       passThrough('--suppress-warnings');
     }),
     new OptionHandler('--fatal-warnings', passThrough),
     new OptionHandler('--suppress-hints',
                       (_) => diagnosticHandler.showHints = false),
     new OptionHandler(
         '--output-type=dart|--output-type=dart-multi|--output-type=js',
         setOutputType),
     new OptionHandler('--use-cps-ir', passThrough),
+    new OptionHandler('--use-frequency-naming', passThrough),
     new OptionHandler('--verbose', setVerbose),
     new OptionHandler('--version', (_) => wantVersion = true),
     new OptionHandler('--library-root=.+', setLibraryRoot),
     new OptionHandler('--out=.+|-o.*', setOutput, multipleArguments: true),
     new OptionHandler('--allow-mock-compilation', passThrough),
     new OptionHandler('--minify|-m', implyCompilation),
     new OptionHandler('--preserve-uris', passThrough),
     new OptionHandler('--force-strip=.*', setStrip),
     new OptionHandler('--disable-diagnostic-colors',
                       (_) => diagnosticHandler.enableColors = false),
@@ skipping 75 matching lines @@
                 "'--output-type=dart'.");
   }
   if (arguments.isEmpty) {
     helpAndFail('No Dart file specified.');
   }
   if (arguments.length > 1) {
     var extra = arguments.sublist(1);
     helpAndFail('Extra arguments: ${extra.join(" ")}');
   }
 
   if (checkedMode && trustTypeAnnotations) {

[sra1, 2015/07/01 04:11:09]

Maybe put a check like this that the experimental option is valid only with
--minify

[herhut, 2015/07/02 08:54:51]

As I now use --no-frequency-based-minification, I would like to allow the one
without the other, so that I can configure minification in an alias and still
turn it on or off with a single flag.

     helpAndFail("Option '--trust-type-annotations' may not be used in "
                 "checked mode.");
   }
 
   if (packageRoot != null && packageConfig != null) {
     helpAndFail("Cannot specify both '--package-root' and '--packages.");
   }
 
   if ((analyzeOnly || analyzeAll) && !optionsImplyCompilation.isEmpty) {
     if (!analyzeOnly) {
@@ skipping 221 matching lines @@
         https://dart-lang.github.io/dump-info-visualizer/
     This feature is currently not supported in combination with the
     '--output-type=dart' option.
 
   --generate-code-with-compile-time-errors
     Generates output even if the program contains compile-time errors. Use the
     exit code to determine if compilation failed.
 
   --use-cps-ir
     Experimental.  Use the new CPS based backend for code generation.
+
+  --use-frequency-naming
+    Experimental.  Use the new frequency based minifying namer.
 '''.trim());
 }
 
 void helpAndExit(bool wantHelp, bool wantVersion, bool verbose) {
   if (wantVersion) {
     var version = (BUILD_ID == null)
         ? '<non-SDK build>'
         : BUILD_ID;
     print('Dart-to-JavaScript compiler (dart2js) version: $version');
   }
@@ skipping 94 matching lines @@
       } else if (exitCode == 253) {
         print(">>> TEST CRASH");
       } else {
         print(">>> TEST FAIL");
       }
       stderr.writeln(">>> EOF STDERR");
       subscription.resume();
     });
   });
 }