Add a finalize incremental marking mode for CollectAllGarbage to finalize incremental marking when incremental marking is in progress, but we want a full gc at a given CollectAllGarbage call site.

Default mode for CollectAllGarbage is finalize incremental marking and perform a full GC.

BUG=

Review URL: https://codereview.chromium.org/1082973003

Cr-Commit-Position: refs/heads/master@{#27831}