Checking for MutationObserver not in global

At the moment the scheduler checks MutationObserver and then assigning global.MutationObserver - causes a lot of fun in IE 11 extensions.
Merge pull request #114 from benjamingr/patch-2

Checking for MutationObserver not in global
track active domain for nextTick for node.js 0.10.xx.

Closes #124
Merge branch 'master' of github.com:petkaantonov/bluebird
deprecate Promise.prototype.spawn
Simplify nextTick bug workaround

Fixes #129
Merge branch 'master' of github.com:petkaantonov/bluebird
deprecate Promise.prototype.spawn
Simplify nextTick bug workaround

Fixes #129
Remove describe.only as it blocks other tests to run

I used it to filter out other tests to speed up the development, but forgot to remove before i had sent previous PR to fix the issue with process.nextTick. My bad.
Implement addYieldHandler
Merge branch 'master' of github.com:petkaantonov/bluebird
bundle
add a test for addYieldHandler
add option to specify node11 path
add more yield handler tests
add some later browsers
Fix #135
Merge branch 'master' of github.com:petkaantonov/bluebird
implement promise tap