When copying a code block using Safari, the line numbers are also copied

Issue Summary

When copying a code block using Safari, the line numbers are also copied

Steps to Reproduce

1. On a Jira ticket, add a code snippet/block
2. Copy the code using Safari
3. Paste the code on an editor like Sublime

Expected Results

When pasting the code, it will be pasted only the text/code

Actual Results

It shows the line numbers (only the number of the first line is not copied) 

Workaround

Use another browser like Chrome or Firefox.