DevTools Timeline: show frame bars and delimiters on flame chart

BUG=398789

Review URL: https://codereview.chromium.org/426263003

git-svn-id: svn://svn.chromium.org/blink/trunk@179295 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Oilpan: Avoid crashes in MemoryCache-related tests.

r179210 added GC to runHelper(). However it exposed MemoryCache-related bugs in
Oilpan. We'll investigate the root cause soon.

BUG=393516
TBR=yhirano@chromium.org,oilpan-reviews@chromium.org

Review URL: https://codereview.chromium.org/437503002

git-svn-id: svn://svn.chromium.org/blink/trunk@179296 bbb929c8-8fbe-4397-9dbb-9b2b20218538