[dartdevc] Add `packages` arg for creating the DDC SDK from kernel

Copied from a change by keertip@ from internal repo.
Original change ID: 253076358

Change-Id: I997ffe7c4fa0588689a2562b7b1dcd5c01837919
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/106002
Reviewed-by: Vijay Menon <vsm@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>
diff --git a/pkg/dev_compiler/tool/kernel_sdk.dart b/pkg/dev_compiler/tool/kernel_sdk.dart
index 0366522..b8d2311 100755
--- a/pkg/dev_compiler/tool/kernel_sdk.dart
+++ b/pkg/dev_compiler/tool/kernel_sdk.dart
@@ -31,7 +31,8 @@
   var parser = ArgParser()
     ..addOption('output')
     ..addOption('libraries',
-        defaultsTo: path.join(ddcPath, '../../sdk/lib/libraries.json'));
+        defaultsTo: path.join(ddcPath, '../../sdk/lib/libraries.json'))
+    ..addOption('packages', defaultsTo: path.join(ddcPath, '../../.packages'));
   var parserOptions = parser.parse(args);
 
   var outputPath = parserOptions['output'] as String;
@@ -43,7 +44,7 @@
   }
 
   var librarySpecPath = parserOptions['libraries'] as String;
-  var packagesPath = path.join(ddcPath, '../../.packages');
+  var packagesPath = parserOptions['packages'] as String;
 
   var target = DevCompilerTarget(TargetFlags());
   void onDiagnostic(DiagnosticMessage message) {