Fix the pubspec and warnings in pkg/kernel.

pkg/kernel/pubspec.yaml

Index: pkg/kernel/pubspec.yaml
diff --git a/pkg/kernel/pubspec.yaml b/pkg/kernel/pubspec.yaml
index b4a2c04870d1f030a9f3dd5e171497ffb12cc99c..d4f3420222646288c9f8de976468e6d4c7e1a14f 100644
--- a/pkg/kernel/pubspec.yaml
+++ b/pkg/kernel/pubspec.yaml
@@ -6,8 +6,7 @@ homepage: https://github.com/dart-lang/kernel
 environment:
   sdk: ">=1.8.0"
 dependencies:
-  # We import some of the analyzer's internal files, so lock the patch version.
-  analyzer: 0.29.0
+  analyzer: ^0.29.0
   path: ^1.3.9
   args: ^0.13.4
   logging: ^0.11.2
@@ -16,3 +15,5 @@ dev_dependencies:
   test: ^0.12.15+6
   stack_trace: ^1.6.6
   ansicolor: ^0.0.9
+dependency_overrides:
+  analyzer: {path: ../analyzer}