Simplify constant pool usage in x64 code generator (by removing extra argument

runtime/vm/object_x64_test.cc

Index: runtime/vm/object_x64_test.cc
diff --git a/runtime/vm/object_x64_test.cc b/runtime/vm/object_x64_test.cc
index b8914e0ab274737fe76e98587356b2b350e61f05..639d8d0ac01e4e559babb8bd2cbd15a9a81cb317 100644
--- a/runtime/vm/object_x64_test.cc
+++ b/runtime/vm/object_x64_test.cc
@@ -35,8 +35,8 @@ void GenerateEmbedStringInCode(Assembler* assembler, const char* str) {
   const String& string_object =
       String::ZoneHandle(String::New(str, Heap::kOld));
   __ pushq(PP);  // Save caller's pool pointer and load a new one here.
-  __ LoadPoolPointer(PP);
-  __ LoadObject(RAX, string_object, PP);
+  __ LoadPoolPointer();
+  __ LoadObject(RAX, string_object);
   __ popq(PP);  // Restore caller's pool pointer.
   __ ret();
 }