Simulator specific code that is the same on all platforms as well as...

Simulator specific code that is the same on all platforms as well as TickSample instance retrieval extracted into SampleHelper class.

Drive-by: extracted platform-independent pieces of Sampler::PlatformData into PlatformDataCommon.

BUG=None
R=loislo@chromium.org, svenpanne@chromium.org

Review URL: https://codereview.chromium.org/15957005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14910 ce2b1a6d-e550-0410-aec6-3dcde31c8c00