ART: ArrayGet hoisting restriction added.

Currently if we hoist ArrayGet from loop there is no guarantee
that insn will be executed at runtime. Because of that we could
face issues like crashes in generated code.

This patch introduces restriction for ArrayGet hoisting. We say
that ArrayGet execution is guaranteed at least one time if its bb
dominates all exit blocks.

Signed-off-by: Anton Shamin <anton.shamin@intel.com>

(cherry picked from commit f89381fe)

BUG=29145171

Change-Id: Ia5664dedb1543d78a7b4038801b8372572f069f6