* Preserve original quotes when rewriting CSS url() paths - important for inline SVG files which often have spaces
* Found an example in the wild with the 'charset=' part left off. This is supported by https://css-tricks.com/lodge/svg/09-svg-data-uris/ ... not sure why we aren't just testing for the 'data:' prefix here?
* Not sure why this is now coming back with a double quote after recent changes here; it's supposed to preserve the single quote from style.css??
* Add a `slimDOM` option to strip out unnecessary parts of the DOM in terms of replay
- <script> tags in the <head> take up unnecessary storage space and are often injected semi randomly to become a source of unnecessary variation between recordings of the same thing
- comment tags can be stripped out without affecting display
- future: this option could also turn on more aggressive stripping, e.g. elements that are hidden by CSS (assuming we can handle them becoming visible after mutation events)
* Mark nodes ignored due to slimDOM option, so that they can also be ignored by the mutation observer in rrweb
* Introducing the `ignored` attribute violates the `serializedNodeWithId` type
* slimDOM: Strip out whitespace nodes from <head> element as they have no effect but take up space
- these would otherwise have to be merged after <script> elements are removed; for statcounter usecase, removing
<script> elements is no good if there is still a trace of their presence due to the white space (and hence a variant <head> node is still produced)
- I explored a more radical stripping of all white space nodes, but there is a problem if parent node is <pre> or otherwise rendered with `white-space: pre` and similar.
detecting applied styles with getComputedStyle would be very expensive (I haven't measured it though)
* Export IGNORED_NODE as a constant instead of relying on the hard-to-grok `-2`
* Remove <link rel=preload as=script> which are similarly as useless as <script> tags
* Make slimDOM configurable with the expecations that `slimDOMOptions: true` will only enable non-destructive options (so not all options may be turned on)
* Expand slimDOM to add options to remove more elements from the <head> that should not be necessary in the replayer context
- was making this change for <wix-image> on Wix websites, but discovered after that this has already been done in e4593ff76d
- have tested document.createElement('wix-image') and document.createElement('foo_bar'), but can't find a canonical source for what is allowed in tag names.
- this restriction was originally introduced in #150 to prevent document.createElement('alt=""') i.e. a very malformed tag name
* added src set as a parsed attribute
* added tests
* changed to /a
* added multiple attribute handling
* added better comment
* made snapshot ignore invalid input as if it is invalid input in the original DOM, it should stay invalid in the recreated DOM
* added extra absolute test case
* code style
* addressed comments
