备用版本不兼容的版本限制：
Incompatible version constraints on barback:

Dart Editor版本1.10.0.release（稳定）Dart SDK版本1.10.0

pubspec.yaml

name: project
description: A sample Polymer application
dependencies:
  browser: any
  polymer: any
  observe: any
  bwu_datagrid: any
transformers:
- polymer:
   entry_points: web/project.html

运行pub get

--- 19:11:03 Running pub get on C:\Users\Toshiba\Documents\Dart\project ... ---
Pub get failed, [1] Resolving dependencies...
Incompatible version constraints on barback:
- observe 0.9.1+1 depends on version >=0.9.0 <0.11.0
- pub itself depends on version >=0.13.0 <0.15.3

** Warning: Application may fail to run since packages did not get installed.Try running pub get again. **

我不明白observe我在项目中使用的对象与pub本身之间有什么联系。 你有什么主意吗？