update pubspec.yaml files to reflect actual package usage

Change-Id: I44dd6f5cb69e11a65a8c2b552a54b89ebc5fa4b5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/159161
Commit-Queue: Devon Carew <devoncarew@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

pkg/dart2native/pubspec.yaml

@@ -11,6 +11,6 @@ executables:
 
 dependencies:
    args: ^1.4.0
+   path: any
 
 dev_dependencies:
-

pkg/kernel/pubspec.yaml

@@ -11,6 +11,8 @@ dependencies:
   args: '>=0.13.4 <2.0.0'
   meta: ^1.0.0
 dev_dependencies:
-  expect: any
+  expect:
+    path: ../expect
+  front_end:
+    path: ../front_end
   test: any
-  testing: any