The factors we considered:
- Most measures show IE9 usage is less than half of IE10 and IE11 combined.
- The same measures often show IE9 usage trailing IE8.
- A number of Google properties, including Google Apps, have ended support for IE9.
- The Polymer project limits support to IE10+.
While we regret the impact to developers who would like to continue to support IE9, we are excited about the improvements this change will allow. For example, releases after Dart v1.5 will be able to use typed arrays across all of our libraries. Typed arrays are a web API for efficient access to raw binary data. Expanded use will help simplify and optimize the Dart SDK and enable developers to build faster and better experiences.
Please post on our discussion group if you have questions about our browser support policy or about our plans for typed arrays.