VM: Share object pool entries for optimized static calls.

runtime/vm/assembler_x64.h

Index: runtime/vm/assembler_x64.h
diff --git a/runtime/vm/assembler_x64.h b/runtime/vm/assembler_x64.h
index 30feb10f762604caf3f7de4e504cdd2feded5351..95c474bc5e749e495df7a86a2ce66e1191915777 100644
--- a/runtime/vm/assembler_x64.h
+++ b/runtime/vm/assembler_x64.h
@@ -773,6 +773,10 @@ class Assembler : public ValueObject {
   void J(Condition condition, const StubEntry& stub_entry, Register pp);
   void CallPatchable(const StubEntry& stub_entry);
   void Call(const StubEntry& stub_entry);
+  // Emit a call that shares its object pool entries with other calls
+  // that have the same equivalence marker.
+  void CallWithEquivalence(const StubEntry& stub_entry,
+                           const Object& equivalence);
   // Unaware of write barrier (use StoreInto* methods for storing to objects).
   // TODO(koda): Add StackAddress/HeapAddress types to prevent misuse.
   void StoreObject(const Address& dst, const Object& obj);