Khan/khan-exercises — pull request #57865 by petercollingridge (2013-07-31 19:17:22+00:00)
Title: Avoid expressions and simplify too much

Fix merging issues from #49514 caused by me renaming functions and ensure rational-expressions.js is completely up to date. Also add more unit tests for new functions. Update simplifying_rational_expressions_4.html which I think/hope is the only exercise to use the old function name.