Add missing upvalue in Node.lua
Add CONTRIBUTING.md file
Minor reformatting
implemented Node:insertBefore
Fix Document:adoptNode() to work correctly with previous commit
Add assertNode() helper to Node.lua to simplify error handling
Add Node.insertBefore() to README.md
Make runtests.lua print the offending line of code if an assertion fails
Tweak output format in runtests.lua
Clean up runtests.lua
Add some reusable assertion functions in gumbo/dom/assertions.lua
Add assertions.lua to list of installed modules in Makefile
Clean up test/git-hooks/commit-msg
Make output of commit-msg git hook consistent with runtests.lua
Add assertDocument() and assertElement() and use where appropriate
Rename parse_file to parseFile (with alias for backwards compatibility)
Fix some coding style inconsistencies
Add converted getElementsByClassName() test from web-platform-tests
Add another converted Web Platform test case
Clarify usage section in README.md