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

runtime/vm/code_patcher_x64_test.cc

Index: runtime/vm/code_patcher_x64_test.cc
diff --git a/runtime/vm/code_patcher_x64_test.cc b/runtime/vm/code_patcher_x64_test.cc
index 9ba8d1f4c1c4fd77fe29fe3ae15e8610e48f8f3c..430b56d55c73b17f4894eccd88b40f5083780d8d 100644
--- a/runtime/vm/code_patcher_x64_test.cc
+++ b/runtime/vm/code_patcher_x64_test.cc
@@ -39,7 +39,10 @@ ASSEMBLER_TEST_GENERATE(IcDataAccess, assembler) {
                                                          15,
                                                          1));
 
-  __ LoadObject(RBX, ic_data, PP);
+  // Code accessing pp is generated, but not executed. Uninitialized pp is OK.
+  __ set_constant_pool_allowed(true);
+
+  __ LoadObject(RBX, ic_data);
   ExternalLabel target_label(StubCode::OneArgCheckInlineCacheEntryPoint());
   __ CallPatchable(&target_label);
   __ ret();