Actually, this doesn't seem like a spec issue, so unblocking bug 687337.
Created attachment 571026 [details] [diff] [review]
This already has sicking's r+ in bug 694145.
Original landing (https://hg.mozilla.org/integration/mozilla-inbound/rev/eb32aca6d54d) + attempt at bustage fix (https://hg.mozilla.org/integration/mozilla-inbound/rev/5675bf2c7930) backed out for failing to build on any platform:
IDBKeyRange::FromJSVal could possibly use nsContentUtils::XPConnect()->WrapJS.
Also, I wonder if Bug 709569 could reduce some manual JS API usage, or if some new features
should be added to the tool.