dart2js: Added support for writing dependency information into a file.

sdk/lib/_internal/compiler/implementation/dart2js.dart

 // Copyright (c) 2012, 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;
 
 import 'dart:io';
 import 'dart:uri';
 import 'dart:utf';
 
@@ skipping 91 matching lines @@
     if (argument == '--output-type=dart') {
       outputLanguage = OUTPUT_LANGUAGE_DART;
       if (!explicitOut) {
         out = cwd.resolve('out.dart');
         sourceMapOut = cwd.resolve('out.dart.map');
       }
     }
     passThrough(argument);
   }
 
+  String getDepsOutput(Map<String, SourceFile> sourceFiles) {
+    var filenames = new List.from(sourceFiles.keys);
+    filenames.sort();
+    return Strings.join(filenames, "\n");
+  }
+
   setStrip(String argument) {
     stripArgumentSet = true;
     passThrough(argument);
   }
 
   handleShortOptions(String argument) {
     var shortOptions = argument.substring(1).splitChars();
     for (var shortOption in shortOptions) {
       switch (shortOption) {
         case 'v':
@@ skipping 154 matching lines @@
   // directly. In effect, we don't support truly asynchronous API.
   String code = api.compile(uri, libraryRoot, packageRoot, provider, handler,
                             options).value;
   if (code == null) {
     fail('Error: Compilation failed.');
   }
   String sourceMapFileName =
       sourceMapOut.path.substring(sourceMapOut.path.lastIndexOf('/') + 1);
   code = '$code\n//@ sourceMappingURL=${sourceMapFileName}';
   writeString(out, code);
+  writeString(new Uri.fromString('$out.deps'), getDepsOutput(sourceFiles));
   int bytesWritten = code.length;
   info('compiled $dartBytesRead bytes Dart -> $bytesWritten bytes '
        '$outputLanguage in ${relativize(cwd, out, isWindows)}');
   if (!explicitOut) {
     String input = uriPathToNative(arguments[0]);
     String output = relativize(cwd, out, isWindows);
     print('Dart file $input compiled to $outputLanguage: $output');
   }
 }
 
@@ skipping 130 matching lines @@
     } catch (ignored) {
       print('Internal error: error while printing exception');
     }
     try {
       print(trace);
     } finally {
       exit(253); // 253 is recognized as a crash by our test scripts.
     }
   }
 }