dart2js: add --preserve-uris flag.

sdk/lib/_internal/compiler/implementation/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:io'
     show exit, File, FileMode, Platform, RandomAccessFile, FileSystemException,
@@ skipping 270 matching lines @@
                       (_) => diagnosticHandler.showHints = false),
     new OptionHandler(
         '--output-type=dart|--output-type=dart-multi|--output-type=js',
         setOutputType),
     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),
     new OptionHandler('--enable-diagnostic-colors',
                       (_) => diagnosticHandler.enableColors = true),
     new OptionHandler('--enable[_-]checked[_-]mode|--checked',
                       (_) => setCheckedMode('--enable-checked-mode')),
     new OptionHandler('--enable-concrete-type-inference',
                       (_) => implyCompilation(
                           '--enable-concrete-type-inference')),
@@ skipping 216 matching lines @@
   --enable-diagnostic-colors
     Add colors to diagnostic messages.
 
   --terse
     Emit diagnostics without suggestions for how to get rid of the diagnosed
     problems.
 
   --show-package-warnings
     Show warnings and hints generated from packages.
 
+  --preserve-uris
+    Preserve the source URIs in the reflection data. Without this flag the
+    `uri` getter for `LibraryMirror`s is mangled in minified mode.
+
   --csp
     Disables dynamic generation of code in the generated output. This is
     necessary to satisfy CSP restrictions (see http://www.w3.org/TR/CSP/).
 
 The following options are only used for compiler development and may
 be removed in a future version:
 
   --output-type=dart
     Output Dart code instead of JavaScript.
 
@@ skipping 128 matching lines @@
       } else {
         print(">>> TEST FAIL");
       }
       stderr.writeln(">>> EOF STDERR");
       runJob();
     });
   }
 
   runJob();
 }