[spec] Fix Katex hacks 2

Author: rossberg

document/core/util/mathjax2katex.py

@@ -67,10 +67,8 @@ def ReplaceMath(cache, data):
   #data = data.replace('\\)', '')
   data = re.sub('^\\\\\\(', '', data)
   data = re.sub('\\\\\\)$', '', data)
-  #data = data.replace('\\[', '')
-  #data = data.replace('\\]', '')
-  data = re.sub('^\\\\\\[', '', data)
-  data = re.sub('\\\\\\)]$', '', data)
+  data = data.replace('\\[', '')
+  data = data.replace('\\]', '')
   data = data.replace('\\DOUBLESLASH', '\\\\')
   data = data.replace('\u2019', '\'')       # "Right Single Quotation Mark" messed up by Bikeshed
   data = data.replace('\\hfill', ' ')