fix a coiple of SyntaxWarning on python 3.8

Lib/fontTools/feaLib/parser.py

@@ -705,7 +705,7 @@ class Parser(object):
         else:
             keyword = None
         self.expect_symbol_(";")
-        if len(new) is 0 and not any(lookups):
+        if len(new) == 0 and not any(lookups):
             raise FeatureLibError(
                 'Expected "by", "from" or explicit lookup references',
                 self.cur_token_location_)

Lib/fontTools/mtiLib/__init__.py

@@ -854,7 +854,7 @@ def parseLookup(lines, tableTag, font, lookupMap=None):
 
 	lookup.SubTable = subtables
 	lookup.SubTableCount = len(lookup.SubTable)
-	if lookup.SubTableCount is 0:
+	if lookup.SubTableCount == 0:
 		# Remove this return when following is fixed:
 		# https://github.com/fonttools/fonttools/issues/789
 		return None