Auto-bind before getDefaultProps

Fixes #1595.
Fix EnterLeaveEventPlugin-test in IE10

Previously this was failing because iframeDocument.body wasn't properly initialized. Creating the document this way seems to work in all environments

Test Plan: Ran the test in jest, phantomjs, IE10, Chrome, and Firefox.
Fix submit-button value test in IE10

Test Plan: Ran test in jest, phantomjs, IE10, Chrome, and Firefox.
Fix PropTypes test in IE10

Test Plan: Ran the test in jest, phantomjs, IE10, Chrome, and Firefox.
Prevent null reference access when unsetting styles
Merge pull request #1597 from spicyj/defaultprops-autobind

Auto-bind before getDefaultProps
Merge pull request #1660 from spicyj/test-ie10-proptypesname

Fix PropTypes test in IE10
Merge pull request #1671 from gasi/fix-unset-style

Prevent null reference access when unsetting styles
Merge pull request #1659 from spicyj/test-ie10-iframe

Fix EnterLeaveEventPlugin-test in IE10
Merge pull request #1658 from spicyj/test-ie10-submit-label

Fix submit-button value test in IE10