Start using operator/operands internally in Filter class.

By having Filter.canonicalize_tuple() call filter_term(),
we make it so that Filter objects get operator/operand
fields in their terms when we initialize this.

This mostly caused test breakage for tests that were doing
assert.deepEqual; now we just check to make sure that the
field we need are there.

(imported from commit 63b2516dc72edeb11e76a1fa4442570b9c605baa)

static/js/filter.js

@@ -103,7 +103,7 @@ Filter.canonicalize_tuple = function (tuple) {
     }
 
     // We may want to consider allowing mixed-case operators at some point
-    return [operator, operand];
+    return filter_term(operator, operand);
 };