Re-enable option for message pump optimization

Re-enable option for message pump optimization

It was disabled by [1] because of regression in touch/click behaviour
in WCS test pages like gesture.html and select_picker_test.html.

1.  Fix the implementation of timer delay code. The code previously tried to
micro-manage timer delays. The intention of those delays was to make code
more robust. Unfortunately it would lead to perpetually postponing one task
instead of spawning new ones. Drop the code adding arbitrary delays.

2.  Make "limit-memory-allocation-in-schedule-delayed-work" flag be enabled
by default again.

[1] http://165.213.202.130/gerrit/#/c/83920/

Original beta/m42 patch: http://165.213.202.130/gerrit/#/c/84369/

Bug: http://web.sec.samsung.net/bugzilla/show_bug.cgi?id=14786

Reviewed by: a1.gomes, msu.koo, sns.park

Change-Id: I1be8b12e84d6a1678e6ab070cf79868076bae5c4
Signed-off-by: Pawel Forysiuk <p.forysiuk@samsung.com>