Version constraint cleanup.

[email protected]

Review URL: https://codereview.chromium.org//1180943003.

Author: pq

pkg/analyzer/pubspec.yaml

@@ -4,12 +4,12 @@ author: Dart Team <[email protected]>
 description: Static analyzer for Dart.
 homepage: http://www.dartlang.org
 environment:
-  sdk: '>=0.8.10+6 <2.0.0'
+  sdk: '>=1.8.0 <2.0.0'
 dependencies:
-  args: <0.14.0
+  args: '>=0.12.1 <0.14.0'
   path: '>=0.9.0 <2.0.0'
-  plugin: <0.2.0
-  watcher: '>=0.9.0 <0.10.0'
+  plugin: ^0.1.0
+  watcher: ^0.9.0
   yaml: ^2.1.2
 dev_dependencies:
   typed_mock: '>=0.0.4 <1.0.0'