Set isInTransaction to false even if close throws

If a transaction wrapper's closer throws (such as flushBatchedUpdates in ReactDefaultBatchingStrategy) then we still want to properly deinitialize the transaction by setting isInTransaction to false. Without this, we can't reuse the transaction object (in this case, all future batched updates would fail because nested transactions aren't allowed).
Small comment grammar fix in ReactComponent.js
remove comma in comment
Add onReset event for forms

Test Plan:
Tested in Chrome and IE8.
Merge pull request #1042 from adelevie/master

Small grammar fix in ReactComponent.js
Update complementary-tools.md
[Docs] Hide compiled js tab in jsx-compiler.html

Fixes #1049
Disable source maps when defineProperty is missing

Fixes #1053.
Add warnings when accessing properties/methods on unmounted components

This creates a membrane around the React component prototype. It warns if you
try to access properties on the component before it's unmounted. Before it's
mounted, it should be considered a descriptor and not an actual instance.

The workaround, for unknown types, is to access the constructor using
component.type which has static methods on it.
Merge pull request #1055 from spicyj/jsx-transformer-ie8

Disable source maps when defineProperty is missing
Merge pull request #1021 from spicyj/close-finally

Set isInTransaction to false even if close throws
Merge pull request #1048 from spicyj/form-onreset

Add onReset event for forms
Disable guarding in ReactErrorUtils

With #1021 and #1022, I believe this makes it so React never wraps user code in a try/catch. I left in the calls to ReactErrorUtils.guard because it sounds like FB code finds them useful.
Update videos.md

There is a better video clip for the Meteor devshop
Merge pull request #1046 from spicyj/errutils

Disable guarding in ReactErrorUtils
[perf] Measure exclusive render time

Piece of https://github.com/facebook/react/pull/962
[perf] Log DOM time

Log the time it takes to perform all DOM operations
[perf] Measure flush time

This is so we can look at a given flush to determine total time spent in React vs DOM, and which components ended up generating DOM ops.
[perf] Change how ReactDefaultPerf is injected

ReactDefaultPerf should inject itself when require()'d. This continues to support the ?react_perf use case for logging on initial page load.
Rewrite ReactTransitionGroup

The key idea here is that you're always rendering `this.state.children`, not
`this.props.children`. When combined with `cloneWithProps()` this means we can
keep them in the DOM as long as we want. We add new children and reactively
update existing ones using `setState()` inside of `componentWillReceiveProps()`
so `this.state.children` always has the latest versions of components. Since we
may be keeping old components around that are no longer in
`this.props.children` we need a way to figure out where they should be inside
of the combined `this.state.children` list.  `ReactTransitionChildMapping` does
this for us.

Based on that infrastructure we can build the interface we always wanted: enter
and leave lifecycle hooks.

When a component is added to the DOM, `componentWillEnter(callback)` gets
called. Call the callback when you're done animating and `componentDidEnter()`
will be called.

When a component is about to be removed from the DOM,
`componentWillLeave(callback)` gets called. Call the callback when you're done
animating and `componentDidLeave()` will be called and the component will
*actually* be removed from the DOM. It won't be removed until you call the
callback.

These also handle "concurrent" changes. If you "stack" enter/leaves of a single
component before the animation has completed, it will block out all of those
animations until the current animation completes, and then finally it will
animate 0 or 1 times to get itself into the desired current state. This is what
differentiates `componentWillEnter()` from `componentDidMount()`.

The next step would be to build `componentDidReorder()`.

I've built `ReactCSSTransitionGroup` which is identical to the old
`ReactTransitionGroup` and codemodded the callsites.