RFR - JDK-8215682 - Remove compiler support for Raw String Literals from JDK 12

[Jim Laskey]

Looking for reviewers to make sure this CSR passes muster.

CSR: https://bugs.openjdk.java.net/browse/JDK-8215682 
<https://bugs.openjdk.java.net/browse/JDK-8215682>

Thank you.

Cheers,

— Jim