Convert Chrome extension to bookmarklet
Conversion to a bookmarklet is impossible for extensions that use privileged chrome API available only for Chrome apps and extensions, in this case chrome.contentSettings.javascript.set.
The root cause - memory hogging by an extension - can be resolved by switching from a persistent background page to an event page that is unloaded when an extension is not used.
You may nag the author of that extension to do so.
Unfortunately, most of the extension authors appear to be unaware.
Another possibility is to edit the extension's manifest.json manually by adding "persistent": false as shown in the event page docs (don't forget the comma), then load it locally. Some extensions will fail since switching to an event page may require reworking of code.