Set minimum scrollback value to number of rows if needed on resize

[irokas]

I was not able to implement a test because I could not get jsdom to work in test.js.

@Tyriar Any ideas on how I can write this test?

[coveralls]

Coverage decreased (-0.03%) to 69.651% when pulling 60348d1 on irokas:Rows-fix into 31aab8e on sourcelair:master.

[coveralls]

Coverage decreased (-0.03%) to 69.651% when pulling 0a5d7a7 on irokas:Rows-fix into 31aab8e on sourcelair:master.

[Tyriar]

@irokas yeah there aren't any tests for resize yet, hopefully we can get around to better testing on the Terminal class when the TypeScript migration finishes.

[coveralls]

Coverage decreased (-0.03%) to 69.637% when pulling af0030b on irokas:Rows-fix into 934ca65 on sourcelair:master.