Mark more roots.

This is most of the stuff. (Everything that currently exists, though there's
more to come.)

Change-Id: I235a21b006820a027c494374a5b52ffefed89c32
diff --git a/src/class_linker.h b/src/class_linker.h
index 4702a57..3f95b8d 100644
--- a/src/class_linker.h
+++ b/src/class_linker.h
@@ -122,7 +122,7 @@
     return boot_class_path_;
   }
 
-  void VisitRoots(Heap::RootVistor* root_visitor, void* arg) const;
+  void VisitRoots(Heap::RootVisitor* visitor, void* arg) const;
 
   const DexFile& FindDexFile(const DexCache* dex_cache) const;
   DexCache* FindDexCache(const DexFile& dex_file) const;