Add histograms to track fraction of heap spaces and percentage of generated crankshaft code.

BUG=None
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/27023003

Patch from Ross McIlroy <rmcilroy@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17198 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Retire concurrent recompilation delay for non-stress testing.

Instead, we block concurrent recompilation until unblocked. This makes
affected tests more predictable and run shorter.

R=jkummerow@chromium.org
BUG=

Review URL: https://codereview.chromium.org/26758003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17199 ce2b1a6d-e550-0410-aec6-3dcde31c8c00