- Implement package map parameter when spawning isolate.

runtime/bin/builtin.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 builtin;
 // NOTE: Do not import 'dart:io' in builtin.
 import 'dart:async';
 import 'dart:collection';
 import 'dart:_internal';
 import 'dart:isolate';
@@ skipping 496 matching lines @@
       _log("Skipping dummy deferred request.");
     }
   });
 
   if (_traceLoading) {
     _log("Requested packages map at '$packagesUri'.");
   }
 }
 
 
+// Embedder Entrypoint:
+// Add mapping from package name to URI.
+void _addPackageMapEntry(String key, String value) {
+  if (!_setupCompleted) {
+    _setupHooks();
+  }
+  if (_traceLoading) {
+    _log("Adding packages map entry: $key -> $value");
+  }
+  if (_packageRoot != null) {
+    if (_traceLoading) {
+      _log("_packageRoot already set: $_packageRoot");
+    }
+    throw "Cannot add package map entry to an exisiting package root.";
+  }
+  if (_packagesPort != null) {
+    if (_traceLoading) {
+      _log("Package map load request already pending.");
+    }
+    throw "Cannot add package map entry during package map resolution.";
+  }
+  if (_packageMap == null) {
+    _packageMap = new Map<String, Uri>();
+  }
+  _packageMap[key] = _workingDirectory.resolve(value);
+}
+
+
 void _asyncLoadError(_LoadRequest req, _LoadError error, StackTrace stack) {
   if (_traceLoading) {
     _log("_asyncLoadError(${req._uri}), error: $error\nstack: $stack");
   }
   if (req._tag == _Dart_kResourceLoad) {
     Completer c = req._context;
     c.completeError(error, stack);
   } else {
     String libraryUri = req._context;
     if (req._tag == _Dart_kImportTag) {
@@ skipping 272 matching lines @@
 }
 
 
 // Register callbacks and hooks with the rest of the core libraries.
 _setupHooks() {
   _setupCompleted = true;
   VMLibraryHooks.resourceReadAsBytes = _resourceReadAsBytes;
   VMLibraryHooks.getPackageRoot = _getPackageRoot;
   VMLibraryHooks.getPackageMap = _getPackageMap;
 }