instancer: don't break on unsupported condition formats

continue checking subsequent condition tables in case the other may
be format=1 and may reference a pinned axis; in which case, these
conditions need to be dropped from the condition set, or the whole
record needs to be dropped if the instance coordinate is outside the
condition range.
Condition tables within a condition set are associated with a AND
boolean operator, so if any one doesn't match, the whole set doesn't
apply. Even if we don't recognize one condition format, if we do
ascertain that another condition table does not match the current
partial instance location, we can drop the FeatureVariation record
since it doesn't apply.

Lib/fontTools/varLib/instancer.py

@@ -474,7 +474,6 @@ def _instantiateFeatureVariations(table, fvarAxes, location):
                 )
                 applies = False
                 newConditions.append(condition)
-                break
 
         if retainRecord and newConditions:
             record.ConditionSet.ConditionTable = newConditions

Tests/varLib/instancer_test.py

@@ -1316,18 +1316,22 @@ class InstantiateFeatureVariationsTest(object):
                 )
             ]
         )
-        gsub = font["GSUB"].table
-        featureVariations = gsub.FeatureVariations
+        featureVariations = font["GSUB"].table.FeatureVariations
         rec1 = featureVariations.FeatureVariationRecord[0]
+        assert len(rec1.ConditionSet.ConditionTable) == 2
         rec1.ConditionSet.ConditionTable[0].Format = 2
 
         with CapturingLogHandler("fontTools.varLib.instancer", "WARNING") as captor:
-            instancer.instantiateFeatureVariations(font, {"wght": 0})
+            instancer.instantiateFeatureVariations(font, {"wdth": 0})
 
         captor.assertRegex(
             r"Condition table 0 of FeatureVariationRecord 0 "
             r"has unsupported format \(2\); ignored"
         )
 
-        # check that record with unsupported condition format is kept
+        # check that record with unsupported condition format (but whose other
+        # conditions do not reference pinned axes) is kept as is
+        featureVariations = font["GSUB"].table.FeatureVariations
         assert featureVariations.FeatureVariationRecord[0] is rec1
+        assert len(rec1.ConditionSet.ConditionTable) == 2
+        assert rec1.ConditionSet.ConditionTable[0].Format == 2