VM: Align implementations of assembler constant pools.

runtime/vm/assembler_x64.h

Index: runtime/vm/assembler_x64.h
===================================================================
--- runtime/vm/assembler_x64.h	(revision 43497)
+++ runtime/vm/assembler_x64.h	(working copy)
@@ -745,11 +745,6 @@
 
   void Drop(intptr_t stack_elements, Register tmp = TMP);
 
-  enum Patchability {
-    kPatchable,
-    kNotPatchable,
-  };
-
   bool allow_constant_pool() const {
     return allow_constant_pool_;
   }
@@ -900,7 +895,7 @@
   const ZoneGrowableArray<intptr_t>& GetPointerOffsets() const {
     return buffer_.pointer_offsets();
   }
-  const GrowableObjectArray& object_pool() const { return object_pool_; }
+  const GrowableObjectArray& object_pool() const { return object_pool_.data(); }
 
   void FinalizeInstructions(const MemoryRegion& region) {
     buffer_.FinalizeInstructions(region);
@@ -1033,14 +1028,8 @@
   AssemblerBuffer buffer_;
 
   // Objects and jump targets.
-  GrowableObjectArray& object_pool_;
+  ObjectPool object_pool_;
 
-  // Patchability of pool entries.
-  GrowableArray<Patchability> patchable_pool_entries_;
-
-  // Hashmap for fast lookup in object pool.
-  DirectChainedHashMap<ObjIndexPair> object_pool_index_table_;
-
   intptr_t prologue_offset_;
 
   class CodeComment : public ZoneAllocated {
@@ -1061,9 +1050,6 @@
   GrowableArray<CodeComment*> comments_;
   bool allow_constant_pool_;
 
-  intptr_t FindObject(const Object& obj, Patchability patchable);
-  intptr_t FindExternalLabel(const ExternalLabel* label,
-                             Patchability patchable);
   intptr_t FindImmediate(int64_t imm);
   void LoadExternalLabel(Register dst,
                          const ExternalLabel* label,