Mozilla isn’t blaming Google here, or they wouldn’t have bothered to fix the bug. When you drill down to the root cause of something, you have to carefully note

Mozilla isn’t blaming Google here, or they wouldn’t have bothered to fix the bug. When you drill down to the root cause of something, you have to carefully note down all the proximate causes that you found along the way, otherwise you won’t have a complete understanding of the problem. In particular, noticing that Google’s machine–generated javascript is doing something allowed but out of the ordinary is important for explaining why you only just now found out about this bug in code that has been working just fine for years.