Fix Internals::forceBlinkGCWithoutV8GC
Fix Internals::forceBlinkGCWithoutV8GC

This CL fixes issue where PerformanceTests/BlinkGC tests were not measured correctly.

Before this CL, forceBlinkGCWithoutV8GC didn't actually force Oilpan precise GC if
lazy sweeping was scheduled.
This CL forces completion of sweeping so that precise GC is actually scheduled to run
at the end of current event loop.

TESTS=PerformanceTests/BlinkGC shows valid numbers >0.5ms
BUG=420515

Review URL: https://codereview.chromium.org/964773002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@191075 bbb929c8-8fbe-4397-9dbb-9b2b20218538

XiaosongWei/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,PeterWangIntel/blink-crosswalk,Pluto-tv/blink-crosswalk,smishenk/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,PeterWangIntel/blink-crosswalk,PeterWangIntel/blink-crosswalk,kurli/blink-crosswalk,Bysmyyr/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,XiaosongWei/blink-crosswalk,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,kurli/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,kurli/blink-crosswalk,PeterWangIntel/blink-crosswalk,XiaosongWei/blink-crosswalk,kurli/blink-crosswalk,smishenk/blink-crosswalk,Pluto-tv/blink-crosswalk,smishenk/blink-crosswalk,smishenk/blink-crosswalk,PeterWangIntel/blink-crosswalk,Pluto-tv/blink-crosswalk,kurli/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,Bysmyyr/blink-crosswalk,smishenk/blink-crosswalk,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,Bysmyyr/blink-crosswalk,Bysmyyr/blink-crosswalk