RFR: 8233364: Fix undefined behavior in Canonicalizer::do_ShiftOp

[Kim Barrett]

> On Nov 2, 2019, at 5:53 AM, Andrew Haley <aph at redhat.com> wrote:
> 
> On 11/2/19 12:07 AM, Kim Barrett wrote:
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8233364
>> 
>> Webrev:
>> https://cr.openjdk.java.net/~kbarrett/8233364/open.00/
> 
> That looks right. Thanks for the cleanup.

Thanks.