Fix type Intersection and Maybe

Intersection of certain constants with bitsets was wrongly non-empty.

R=jarin
BUG=

Committed: https://crrev.com/1328715977ea6a4f806349ec65f5a03567a129d0
Cr-Commit-Position: refs/heads/master@{#30790}

[neis, 2015-09-15 13:49:28]

The CQ bit was checked by neis@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-15 13:49:35]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1343933002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1343933002/1

[commit-bot: I haz the power, 2015-09-15 14:18:20]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-15 14:18:20]

Dry run: This issue passed the CQ dry run.

[Jarin, 2015-09-16 21:23:38]

lgtm, but you are right - the code is on the verge of being unmaintainable. We
need to find a way to simplify this somehow.

[neis, 2015-09-17 08:17:53]

The CQ bit was checked by neis@chromium.org

[commit-bot: I haz the power, 2015-09-17 08:18:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1343933002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1343933002/1

[commit-bot: I haz the power, 2015-09-17 08:52:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-17 08:52:23]

Patchset 1 (id:??) landed as
https://crrev.com/1328715977ea6a4f806349ec65f5a03567a129d0
Cr-Commit-Position: refs/heads/master@{#30790}