Revert "Revert "Add support for booting with a boot classpath not fully AOTed.""

This reverts commit 14bfeddf2e434954f0ca36687ac0fc5dc6412bd3.

Reason for revert: Removes obsolete DCHECK
Bug: 119800099

Change-Id: Ia984f95300c6b96165f0179bfc2f66b012bf5dbe
11 files changed