Test for duplicate symbols/macros (#1955)
Test for duplicate symbols/macros (#1955)

* Test for duplicate symbols/macros

We've had a few cases where we accidentally include the same symbol or macro
definition in both macros.js and symbols.js.  This new test automatically
detects these scenarios during Jest testing.

* Fix lint errors

xymostech/KaTeX,xymostech/KaTeX,xymostech/KaTeX,Khan/KaTeX,xymostech/KaTeX,xymostech/KaTeX,Khan/KaTeX,Khan/KaTeX