Bug 847840 - TEST-UNEXPECTED-FAIL | tests/test-selection.test Selection Listener on frame | Test output exceeded timeout (60s).

Tried to wait the `document-shown` notification before resolve the window, and also move the shutdown functions (`close`, `loader.unload`, `done`) for the test that sometimes is failing.
Ignore removed listeners during dispatch.
Add `off` method to event/target for compatibility with devtools.
Bug 857598: Ensure waiting for session restore event before running the addon.
Remove unnecessary self from page-mod example
Update credits.md
Merge pull request #918 from jryans/master

Remove unnecessary self from page-mod example
Merge pull request #916 from ochameau/bug857598

Bug 857598: Ensure waiting for session restore event before running the addon. r=@mossop
Bug 857750 - TEST-UNEXPECTED-FAIL | tests/test-self.testSelf | self.loadReason is always `startup` on test runs ("install" != "startup")
Merge pull request #919 from ochameau/bug857750

Bug 857750 - TEST-UNEXPECTED-FAIL | tests/test-self.testSelf | self.loadReason is always `startup` on test runs ("install" != "startup") r=mossop
Bug 857750 followup - Change the versionInRange() check to account for the central->aurora merge earlier this week
Merge pull request #921 from KWierso/fixtestself

Bug 857750 followup - Change the versionInRange() check to account for the central->aurora merge earlier this week. r=mossop
url.isValidUrl function, tests, used in Request ctor
Merge pull request #911 from jsantell/request-url-validation-841628

Fixes Bug 841628, Request Constructor Validates URL, r+=@erikvold
Merge pull request #910 from Gozala/bug/event-target-off@856147

Bug 856147 - Add `off` method to event/target for compatibility with devtools. r=@gozala
Bug 855086: Timeouts and empty tests aren't logged correctly. r=ochameau
Merge pull request #909 from Gozala/bug/remove-listeners@856146

fix Bug 856146 - Ignore removed listeners during dispatch. r=@ochameau
Bug 858248: Give testWaitUntilTimeoutInCallback longer to complete.
Rename URL.isValidURL to URL.isValidURI, a=@gozala
Merge pull request #924 from Mossop/bug858248

Bug 858248: Give testWaitUntilTimeoutInCallback longer to complete. r=ochameau