Allow tests to specify a package root.

dart/dart.gyp

Index: dart/dart.gyp
diff --git a/dart/dart.gyp b/dart/dart.gyp
index 3ec8489bf257809e14183f5e76709c72a2427c26..b76a758de5735cd048c36901a4c325c43863b149 100644
--- a/dart/dart.gyp
+++ b/dart/dart.gyp
@@ -13,6 +13,9 @@
       'actions': []
     },
     {
+      # This is the target that is built on the VM build bots.  It
+      # must depend on anything that is required by the VM test
+      # suites.
       'target_name': 'runtime',
       'type': 'none',
       'dependencies': [
@@ -21,6 +24,7 @@
         'runtime/dart-runtime.gyp:run_vm_tests',
         'runtime/dart-runtime.gyp:process_test',
         'runtime/dart-runtime.gyp:test_extension',
+        'packages',
       ],
     },
     {
@@ -104,11 +108,15 @@
       ],
     },
     {
+      # This is the target that is built on the dart2js build bots.
+      # It must depend on anything that is required by the dart2js
+      # test suites.
       'target_name': 'dart2js_bot',
       'type': 'none',
       'dependencies': [
         'third_party/v8/src/d8.gyp:d8',
         'create_sdk',
+        'packages',
       ],
     },
     {
@@ -125,5 +133,12 @@
         'samples/sample_extension/sample_extension.gyp:sample_extension',
       ],
     },
+    {
+      'target_name': 'packages',
+      'type': 'none',
+      'dependencies': [
+        'pkg/pkg.gyp:pkg_packages',
+      ],
+    },
   ],
 }