Avoid flow imports in no-cycle rule

[claramunt]

Avoid flow imports in no-cycle rule
Currently no-cycle rule is not working with babel parser, errors are being skipped due to

if (sourceNode._babelType === 'Literal') {	
  return // no Flow import resolution, workaround for ESLint < 5.x	
}

fixes #1166

[coveralls]

Coverage decreased (-0.002%) to 97.354% when pulling f67bee4 on claramunt:master into db471a8 on benmosher:master.

[coveralls]

Coverage increased (+0.001%) to 97.804% when pulling 52dbd0b on claramunt:master into 15e5c61 on benmosher:master.

[ljharb]

Please don’t close and reopen to kick CI; maintainers can rerun failed builds if needed.

[vikr01]

Already fixed in #1218.

[ljharb]

@vikr01 your PR has fewer code changes, and has appveyor tests failing; this one has decreased coverage, but tests are passing. Can you update yours to include all the test cases here, and see about getting everything green?

[vikr01]

The only new things this PR seems to add are ExportMap.js#L396 and no-cycle.js#L53/54, which are only used by ExportAllDeclaration and ImportDeclaration -- and are not covered by the tests.

Everything else added, including the tests, were copied from #1218.

[ljharb]

@claramunt since #1218 is merged, I've rebased this - the only changes left have no test coverage. Could you add some?

[claramunt]

Sorry for the delay, didn't see the thread. I'm closing this PR since it seems fixed in other merged PR