Making context-matching actually work, and don't check in script tags (fixes redirect to NSFW buttfront.net on Washington Post and others)

There was a stray | at the end of the context-checking regex, which meant that it matched anything that had "" in it - which is everything.  This pretty effectively broke all attempts at context-limiting things as far as I can tell.  I fixed that, and added a couple more words.

I also added a check to not dive into `script` tags, since the contents of script tags are also textNodes, but messing with them can break things.

Which brings us to the Washington Post: these two issues combined for a rather humorous (but annoying) effect.  When you visit the Washington Post's website (and I assume many others) with this extension installed, it delves into the CDN script tag and replaces "buttront.net" with "buttfront.net" (even though there is no appropriate context), which somehow has the effect of redirecting the browser to buttfront.net - which is an existing placeholder site that is nonetheless sometimes NSFW, depending on which load balancer you land on.

Either of these fixes will resolve the WaPo issue - the script tags adds a bit more processing, but also makes the script safer against actually messing things up.