Revert of Introducing the LLVM greedy register allocator.

src/zone-containers.h

Index: src/zone-containers.h
diff --git a/src/zone-containers.h b/src/zone-containers.h
index fc57c04adc56a394241e93380aca9de7cccf328a..0a599bcf2b0501500fc4a17369728a7660cc8107 100644
--- a/src/zone-containers.h
+++ b/src/zone-containers.h
@@ -63,17 +63,6 @@
 };
 
 
-// A wrapper subclass std::priority_queue to make it easy to construct one
-// that uses a zone allocator.
-template <typename T, typename Compare = std::less<T>>
-class ZonePriorityQueue : public std::priority_queue<T, ZoneVector<T>> {
- public:
-  // Constructs an empty list.
-  explicit ZonePriorityQueue(Zone* zone)
-      : std::priority_queue<T, ZoneVector<T>>(Compare(), ZoneVector<T>(zone)) {}
-};
-
-
 // A wrapper subclass for std::queue to make it easy to construct one
 // that uses a zone allocator.
 template <typename T>