Add clearer invariants to composite spec mixing
Add clearer invariant in processUpdates

The `updatedChildren[j].parentNode.removeChild(updatedChildren[j]);` line below can fail if (1) we're moving/moving the same node twice or (2) the node we're looking for is gone completely. This makes it easier to distinguish between the two cases.

Perf shouldn't be a concern here because this is DOM code and invariants are fast in comparison.

Test Plan: grunt test
Merge pull request #1419 from spicyj/inv-process

Add clearer invariant in processUpdates
Merge pull request #1188 from spicyj/comp-spec-inv

Add clearer invariants to composite spec mixing
Allow `false` as an acceptable renderable type value

`false` is renderable.
Make custom PropTypes return error rather than whatever

The new rule for PropTypes is that it should return an error object if validation fails, not throw, not warn.
Add typed ReactLink to ReactProps

Adds a PropType that checks for proper use of the ReactLink API and optionally validates the type of value passed in via the link. Basically, it's a wrapper around PropTypes.shape that hides the implementation of ReactLink.
Remove function wrappers in DOMSelection

There is no point in doing the feature detection on every call, unless there is an IE bug where it is not sure about which support for selection it has (totally plausible).
Fixed a bug in expectRenderedChildAt

React components have _mountIndex, that looks like it is their order in DOM.
If you swap 2 elements in DOM, their order in children array isn't changed, but their _mountIndex is
unbreak server-side/web worker

We're now trying to access document directly at require time. Wrapping in a function prevented that before. But we can simply check what environment we're in first.
fix log spew from ReactDOMInput test

The prop validation threw a warning that either `onChange` or `readOnly` is required. Set the `onChange` where needed.
fix log spew from ReactDOMTextarea test

Similar to previous but for textarea. If `value` is set, we have to also set
`onChange` to avoid warnings.
better error message for React EventPlugin order check

Ran into this while inadvertently requiring multiple React versions in a separate project (`require('react');` vs `require('React');`
fix warnings in ReactComponentLifeCycle test

Don't use inputs to avoid warnings in tests
fix warnings in cloneWithProps test

Don't test refs in this case, already testing warning above
Update videos.md
Remove whitespace_transformer package

This was a one-time use thing, let's get rid of it. If we ever need to
push an update, we'll do it from the 0.9-stable branch.
Split DefaultDOMPropertyConfig

This makes it a little easier to add SVG properties. It also makes use of that injection that we claim is easy to use and will likely start playing a bigger part soon.

Closes #1009
Upgrade jstransform to 4.0

Also enables the object-concise-method transform for --harmony

closes #1438
Don't let new keys on `style` from `transferPropsTo` override old ones

Previous behavior: `transferPropsTo(<div style={{color: 'red'}} />)` would get `color` overriden if we transfer in a `style={{color: 'blue'}}`. This is inconsistent with how other props are transfered.

This simply reverses the order of arguments.

closes #1435