Make patch_sdk step invoke fasta's compile_platform to generate patched_sdk/platform.dill.

tools/patch_sdk.dart

 #!/usr/bin/env dart
 // Copyright (c) 2015, 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.
 
 /// Command line tool to merge the SDK libraries and our patch files.
 /// This is currently designed as an offline tool, but we could automate it.
 
 import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:path/path.dart' as path;
+import 'package:front_end/src/fasta/bin/compile_platform.dart' as
+    compile_platform;
 
 void main(List<String> argv) {
   var base = path.fromUri(Platform.script);
   var dartDir = path.dirname(path.dirname(path.absolute(base)));
 
-  if (argv.length != 4 ||
-      !argv.isEmpty && argv.first != 'vm' && argv.first != 'ddc') {
+  if (argv.length != 5 || (!argv.isEmpty && argv.first != 'vm')) {

[kustermann, 2017/02/23 15:59:38]

We have shortcut operators: Just use

if (argv.length != 5 || argv.first != 'vm') {
}

     var self = path.relative(base);
-    print('Usage: $self MODE SDK_DIR PATCH_DIR OUTPUT_DIR');
+    print('Usage: $self MODE SDK_DIR PATCH_DIR OUTPUT_DIR PACKAGES');
     print('MODE must be one of ddc or vm.');

[kustermann, 2017/02/23 15:59:39]

Remove "ddc or".

 
-    var toolDir = path.relative(path.dirname(base));
-    var sdkExample = path.join(toolDir, 'input_sdk');
-    var patchExample = path.join(sdkExample, 'patch');
-    var outExample =
-        path.relative(path.normalize(path.join('gen', 'patched_sdk')));
+    var repositoryDir = path.relative(path.dirname(path.dirname(base)));
+    var sdkExample = path.relative(path.join(repositoryDir, 'sdk'));
+    var packagesExample = path.relative(path.join(repositoryDir, '.packages'));
+    var patchExample = path.relative(path.join(repositoryDir, 'out', 'DebugX64',
+                                               'obj', 'gen', 'patch'));
+    var outExample = path.relative(path.join(repositoryDir, 'out', 'DebugX64',
+                                             'obj', 'gen', 'patched_sdk'));

[kustermann, 2017/02/23 15:59:39]

final?

     print('For example:');
-    print('\$ $self ddc $sdkExample $patchExample $outExample');
-
-    var repositoryDir = path.relative(path.dirname(path.dirname(base)));
-    sdkExample = path.relative(path.join(repositoryDir, 'sdk'));
-    patchExample = path.relative(path.join(repositoryDir, 'out', 'DebugX64',
-                                           'obj', 'gen', 'patch'));
-    outExample = path.relative(path.join(repositoryDir, 'out', 'DebugX64',
-                                         'obj', 'gen', 'patched_sdk'));
-    print('or:');
     print('\$ $self vm $sdkExample $patchExample $outExample');
 
     exit(1);
   }
 
   var mode = argv[0];
   var input = argv[1];
   var sdkLibIn = path.join(input, 'lib');
   var patchIn = argv[2];
   var sdkOut = path.join(argv[3], 'lib');
+  var packagesFile = argv[4];

[kustermann, 2017/02/23 15:59:38]

final?

 
   var privateIn = path.join(input, 'private');
   var INTERNAL_PATH = '_internal/compiler/js_lib/';
 
   // Copy and patch libraries.dart and version
   var libContents = new File(path.join(sdkLibIn, '_internal',
       'sdk_library_metadata', 'lib', 'libraries.dart')).readAsStringSync();
   var patchedLibContents = libContents;
   if (mode == 'vm') {
     libContents = libContents.replaceAll(
@@ skipping 112 matching lines @@
           contents = _patchLibrary(
               patchFile.path, contents, patchContents);
         }
 
         for (var i = 0; i < outPaths.length; i++) {
           _writeSync(outPaths[i], contents[i]);
         }
       }
     }
   }
+
   if (mode == 'vm') {
-
     for (var tuple in [['_builtin', 'builtin.dart']]) {
       var vmLibrary = tuple[0];
       var dartFile = tuple[1];
 
       // The "dart:_builtin" library is only available for the DartVM.
       var builtinLibraryIn  = path.join(dartDir, 'runtime', 'bin', dartFile);
       var builtinLibraryOut = path.join(sdkOut, vmLibrary, '${vmLibrary}.dart');
       _writeSync(builtinLibraryOut, new File(builtinLibraryIn).readAsStringSync());
     }
 
     for (var file in ['loader.dart', 'server.dart', 'vmservice_io.dart']) {
       var libraryIn  = path.join(dartDir, 'runtime', 'bin', 'vmservice', file);
       var libraryOut = path.join(sdkOut, 'vmservice_io', file);
       _writeSync(libraryOut, new File(libraryIn).readAsStringSync());
     }
   }
+
+  compile_platform.main(<String>[

[kustermann, 2017/02/23 15:59:39]

await compile_platform.main();

+    '--packages', packagesFile, sdkOut, path.join(sdkOut, 'platform.dill')
+  ]);
 }
 
 /// Writes a file, creating the directory if needed.
 void _writeSync(String filePath, String contents) {
   var outDir = new Directory(path.dirname(filePath));
   if (!outDir.existsSync()) outDir.createSync(recursive: true);
 
   new File(filePath).writeAsStringSync(contents);
 }
 
@@ skipping 323 matching lines @@
     if (diff != 0) return diff;
     return end - other.end;
   }
 }
 
 List<SdkLibrary> _getSdkLibraries(String contents) {
   var libraryBuilder = new SdkLibrariesReader_LibraryBuilder(true);
   parseCompilationUnit(contents).accept(libraryBuilder);
   return libraryBuilder.librariesMap.sdkLibraries;
 }