Use stelm.ref helper calls towards array bounds check assertions and range check elimination

[erozenfeld]

In case of generic arrays instantiated over obj-ref, store to array takes place using stelem.ref helper (CORINFO_HELP_ARRADDR_ST). This helper call performs both a null check and array bounds check before assigning the value using a write barrier. Right now neither assertion prop nor range check make use of stelm.ref helper calls to eliminate redundant bounds checks.

category:cq
theme:bounds-checks
skill-level:expert
cost:medium
impact:medium