New test: frame-g010: Multiple named graphs

[pjohnston-wiley]

This follows on from a bug and fix i filed on pyld: issue 81. At @davidlehn 's request i am submitting the test so that future implementations don't make the same mistake.

As far as i can tell there aren't any tests that deal with multiple named graphs yet, so i hope this is useful. Please note that none of the following implementations currently comply with what i think should be the results:

• Stable JSON-LD playground processes the data OK, but omits the children of the two named graphs' @graphs.
• Dev JSON-LD playground barfs. Unless i am missing something in the frame definition (entirely possible), the error message seems to indicate it has lost a property in its lookup table somewhere in applying the framing algorithm. I saw this on some occasions in pyld, though i cannot currently reproduce it there.

TypeError: Cannot read property 'https://json-ld.org/playground-dev/Montague' of undefined

• For pyld, for it to pass i had to explicitly add {"pruneBlankNodeIdentifiers": true} to the framing tests, as well as applying my proposed fix. Since this is being removed from the spec, i figure the implementation itself will catch up in a future iteration.

[gkellogg]

@pjohnston-wiley do you plan to update this PR?

[gkellogg]

Great, thanks!