Check if timeout has expired after processing each sample

Check if timeout has expired after processing each sample

To avoid long intervals between taking samples due to processing all accumulated samples at once, the samples are processed one by one and we check if the sampling interval has elapsed after each step rather than after processing all the samples in the queue.

BUG=v8:2814
R=bmeurer@chromium.org, loislo@chromium.org

Review URL: https://codereview.chromium.org/23583036

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16548 ce2b1a6d-e550-0410-aec6-3dcde31c8c00