hg: amber/amber: Add support for constant patterns

[brian.goetz at oracle.com]

Changeset: 9e4fc2e97fd0
Author:    briangoetz
Date:      2018-10-31 13:21 -0400
URL:       http://hg.openjdk.java.net/amber/amber/rev/9e4fc2e97fd0

Add support for constant patterns

! src/java.base/share/classes/java/lang/compiler/Extractor.java
! src/java.base/share/classes/java/lang/compiler/ExtractorImpl.java
! test/jdk/java/lang/compiler/ExtractorTest.java