Fixed #831
Opera needs same special treatment as webkit for :checked selector
Adding CONTRIBUTING.md Fixes #857
add missing carriage return
Updating formatting and wrapping
Update CONTRIBUTING.md

Removed unnecessary block of text relevant only to the wiki version.
Adding block for Pull Request context
Fixing new issues link
Added Benchmark.js v1.0.0
Added benchmarkjs's nano.jar
Added Benchmark.js license to library LICENSE.md
Tree: Massive speedup in Tree#emptyNode().

Previously, `emptyNode()` triggered a node map reindex for each node
that was removed. This commit modifies `emptyNode()` to remove nodes in
last-first order and avoids the need to reindex.

Previously, emptying a node with 10,000 children took about 17 seconds
in Chrome. After this change, it's nearly instantaneous.
Build tree.
Merge branch 'master' into benchmarkjs
YUI and Loader build for latest Gallery build
Add simple benchmarks for promises
Updated Promise perf tests to work in CI
Merge pull request #6 from derek/promise-bench

Updated Promise perf tests to work in CI
Delete old benchmarks
Update lang-test.js

Unit tests added to trim, trimLeft, and trimRight
Update yui-lang.js