RFR(XS): Matrix inbound regions do not get clear in most of cases

[Aleksey Shipilev]

On 05/16/2017 10:15 PM, Zhengyu Gu wrote:
> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/clean_matrix_inbound/webrev.00/

D'oh. Looks good. Let me do add ASSERT blocks in the follow-up patches.

-Aleksey