Revert "Revert "Make sure that const-class linkage is preserved.""

Fix jdwp getting multiple instances of the same class.
Fix counting "zygote"/"non-zygote" classes in class table.
Fix FindClass() to EnsureResolved() classes added by
a racing thread to the class table.

Test: m test-art-host
Test: art/tools/run-jdwp-tests.sh --mode=host --variant=X64 --debug
Bug: 30627598

This reverts commit ecffc67068a28d55d131553bf915fdb9fafbbc03.

Change-Id: I15807949da4f163c2693fac2fbfc274f17685f8a
diff --git a/compiler/image_writer.h b/compiler/image_writer.h
index 24fad46..ad6ffd8 100644
--- a/compiler/image_writer.h
+++ b/compiler/image_writer.h
@@ -588,7 +588,8 @@
   class FixupVisitor;
   class GetRootsVisitor;
   class NativeLocationVisitor;
-  class NonImageClassesVisitor;
+  class PruneClassesVisitor;
+  class PruneClassLoaderClassesVisitor;
   class VisitReferencesVisitor;
 
   DISALLOW_COPY_AND_ASSIGN(ImageWriter);