Guard against frames across pages, in the profiler.

On Windows, if a page is not touched yet by the stack's thread, the page may be a guard page.

BUG=
R=johnmccutchan@google.com

Review URL: https://codereview.chromium.org//293133007

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@36623 260f80e4-7a28-3924-810f-c04153c831b5
2 files changed