Fix unoptimized code calling a disabled code when --verify-on-transition is enabled.

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
diff --git a/runtime/vm/stub_code_x64.cc b/runtime/vm/stub_code_x64.cc
index 49cb3f3ac9f19858fb097623ac26492b401d4ec3..7ff72e280476d95ac64a316f855bc080feb00458 100644
--- a/runtime/vm/stub_code_x64.cc
+++ b/runtime/vm/stub_code_x64.cc
@@ -1914,11 +1914,12 @@ void StubCode::GenerateOptimizeFunctionStub(Assembler* assembler) {
   __ pushq(RDI);  // Arg0: function to optimize
   __ CallRuntime(kOptimizeInvokedFunctionRuntimeEntry, 1);
   __ popq(RAX);  // Disard argument.
-  __ popq(CODE_REG);  // Get Code object.
+  __ popq(RAX);  // Get Code object.
   __ popq(R10);  // Restore argument descriptor.
-  __ movq(RAX, FieldAddress(CODE_REG, Code::entry_point_offset()));
   __ LeaveStubFrame();
-  __ jmp(RAX);
+  __ movq(CODE_REG, FieldAddress(RAX, Function::code_offset()));
+  __ movq(RCX, FieldAddress(RAX, Function::entry_point_offset()));
+  __ jmp(RCX);
   __ int3();
 }