Show the dependender(s) for missing packages.

sdk/lib/_internal/pub/test/hosted/offline_test.dart

Index: sdk/lib/_internal/pub/test/hosted/offline_test.dart
diff --git a/sdk/lib/_internal/pub/test/hosted/offline_test.dart b/sdk/lib/_internal/pub/test/hosted/offline_test.dart
index 16be30c0c17ba3602b5037623b0c10d73c545305..b799198e3ac68ebd62b0c7fba55b6a27ac2ad203 100644
--- a/sdk/lib/_internal/pub/test/hosted/offline_test.dart
+++ b/sdk/lib/_internal/pub/test/hosted/offline_test.dart
@@ -46,7 +46,7 @@ main() {
       d.appDir({"foo": "any"}).create();
 
       pubCommand(command, args: ['--offline'],
-          error: 'Could not find package "foo" in cache.');
+          error: "Could not find package foo in cache.");
     });
 
     integration('fails gracefully no cached versions match', () {
@@ -60,8 +60,8 @@ main() {
       d.appDir({"foo": ">2.0.0"}).create();
 
       pubCommand(command, args: ['--offline'], error:
-          "Package 'foo' has no versions that match >2.0.0 derived from:\n"
-          "- 'myapp' depends on version >2.0.0");
+          "Package foo has no versions that match >2.0.0 derived from:\n"
+          "- myapp depends on version >2.0.0");
     });
   });
 }