RFR: 8234617: C1: Incorrect result of field load due to missing narrowing conversion

[Sergey Nazarkin]

Original change
https://jira.azulsystems.com/browse/JDK-8234617

I’m not sure 8u need this but the fix reminds me recent BBB issue. 

If we need this the patch is following
webrev
http://cr.openjdk.java.net/~snazarki/jdk8u-dev-webrev/8234617/

c1_GraphBuilder is patched cleanly after path correction
TestPrimitiveConversions.java needs correct Asserts.java path


Sergey