Quoting the article “Google to abandon older browsers” [via @annavester]:
As a result, from 1 August, Google will only support what it calls "modern browsers". By this it means the latest versions and major prior releases of Chrome, Firefox, Internet Explorer and Safari.Comments:As new versions of these are released, Google will get its web services working with that and then drop support for the third-oldest version.
Support in this sense means that Google will only do compatibility testing with more up-to-date browsers. It will not carry out tests with older programmes and can make no guarantees that web services will work with them.