This extends the existing clearing of ICs during GC to incremental
marking in order to prevent cross-context retention that would last
until the next non-incremental GC.

R=erik.corry@gmail.com
TEST=cctest/test-heap/IncrementalMarkingClears[Mono,Poly]morhpicIC

Review URL: https://chromiumcodereview.appspot.com/10831123

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12259 ce2b1a6d-e550-0410-aec6-3dcde31c8c00