Rename Animation.targetElement to target and make read only.
Update tests that reference targetElement
Update KeyframeAnimationEffect to reflect FPWD

- Update KeyframeAnimationEffect API
- Remove Keyframe from API as this is now just a dictionary
- Normalize keyframe dictionaries
- Update algorithm for normalizing (distributing) the list of keyframes
- Update algorithm for sampling a KeyframeAnimationEffect
- Handle interpolating between keyframes with different composite operations
- Remove redundant KeyframeList and GroupedAnimationEffect types
- Remove merge composite operation
- Update tests accordingly

Note that the only substantial change to the tests is in test-compositor.
Address Doug's comments
Update tests added after bootstrap refactor in aac98
Merge pull request #283 from dstockwell/fix-tests

Update tests added after bootstrap refactor in aac98
Merge pull request #280 from dstockwell/anim-target

Rename Animation.targetElement to target and make read only.
Instrument source and generate a small report when '#coverage' specified
Merge pull request #284 from dstockwell/coverage

Instrument source and generate a small report when '#coverage' specified
Implement PseudoElementReference.
Merge pull request #278 from dstockwell/pseudo

Implement PseudoElementReference.
Merge pull request #254 from steveblock/keyframeAnimationEffect

Update KeyframeAnimationEffect to reflect FPWD
Add missing/remove deleted test from testcases.js
Merge pull request #285 from dstockwell/fix-testcases

Add missing/remove deleted test from testcases.js
Fix bootstrap for non-coverage mode
Disable tests failing after new KeyframeAnimationEffect implementation
Disable test-partial-keyframes.html
Fix composite for PathAnimationEffect
Merge pull request #286 from dstockwell/fix-path

Fix composite for PathAnimationEffect
Use awesome new syntax in test-update-state.html