Oilpan: Move core/testing/ to oilpan's heap

This CL moves InternalRuntimeFlags, InternalSettingsGenerated, GCObservation, InternalProfilers, InternalSettings, Internals, LayerRect, LayerRectList, MallocStatistcs and TypeConversions to oilpan's heap.

BUG=340522

Review URL: https://codereview.chromium.org/174533004

git-svn-id: svn://svn.chromium.org/blink/trunk@167587 bbb929c8-8fbe-4397-9dbb-9b2b20218538