Remove ImageWriter::IsInBootOatFile().

It was used only as a pre-condition for a DCHECK() that was
commented-out because of the multi-image implementation.
If it was needed again, ImageWriter::IsInBootImage() should
be a sufficient replacement as it covers oat files.

Also use ImageWriter::IsInBootImage() instead of
Heap::ObjectIsInBootImageSpace().

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Change-Id: Ia64e1e807a2cd24135456ae2294a3e6b9fd16337
2 files changed