JIT: Fix incorrect CHECK

MirMethodLoweringInfo::Resolve() contains a CHECK that fails if the
invoke being resolved is String.<init>().  This changes the invoke_type
to kDirect, and then CHECKs that it is kVirtual, which doesn't work
well.

Change-Id: I2c3afa38533fb39f0b1260968c46b251088e75c8
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>