Also avoid that calling Debug::IsBreakAtReturn causes a full doptimization when there are no break points set. The full deoptimization is caused by Debug::IsBreakAtReturn calling Debug::EnsureDebugInfo which will assume that a break point is now set.

R=svenpanne@chromium.org

BUG=v8:1140
TEST=test/mjsunit/debug-evaluate-locals-optimized.js,test/mjsunit/debug-
evaluate-locals-optimized-doubles.js

Review URL: http://codereview.chromium.org//7307035

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8573 ce2b1a6d-e550-0410-aec6-3dcde31c8c00