The argument comes from the caller, there is absolutely no guarantee that it's in the form KURL expects. This causes assertion failures whenever it's not (e.g. revokeBlobURL("[foo bar]"); For absolute URLs, we should just pass a null base: KURL(KURL(), string). But if it can be relative, a proper base should be passed.
Created attachment 68635 [details] Proposed Patch
Committed as http://trac.webkit.org/changeset/68275.