Send less aggressive pseudo-idle notification after page reload.

V8 now correctly estimates time for mark-compact GC based on previous GCs.

BUG=404020

Review URL: https://codereview.chromium.org/527023002

git-svn-id: svn://svn.chromium.org/blink/trunk@181187 bbb929c8-8fbe-4397-9dbb-9b2b20218538