UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36

Steps to reproduce the problem:
1. Go to https://plnkr.co/edit/5JT0X0whMJ6G7wXZfZNM?p=preview and run the script/test
2. Go to https://plnkr.co/edit/x8skIAMV0P7cpimL4YCS?p=preview and run the script/test
3. Compare the "time needed" that is shown on the right between (1) and (2).

What is the expected behavior?
I expect that the needed time is about the same for both test cases (1) and (2).

What went wrong?
The time needed in testcase (2) is about doubled the time needed in (1). On my computer these are about 100ms in case (1) and 200ms in case (2).

The only difference between the two scripts are the lines:
var object = [1,2,3];
object.constructor = function() {};

Where the second line is not present in testcase (1). So it seems that setting the constructor property of an instance of an array object dramatically slows down the decryption that is done in the rest of the script. I have no clue why this could be and I also think this should not be the case.

Did this work before? N/A 

Chrome version: 71.0.3578.98  Channel: stable
OS Version: 10.0
Flash Version: 

I've tried the same on a Windows 7 Virtual Machine, same error.

In current Firefox and Edge this problem does not occur.