What is the Prince XML value for the engine that has a Gecko value of 'no' and webkit value of 'nightly build'?
CREATE TABLE "grammar_and_rules" (
  "trident" text,
  "gecko" text,
  "web_kit" text,
  "khtml" text,
  "presto" text,
  "prince_xml" text
);
SELECT "prince_xml" FROM "grammar_and_rules" WHERE "gecko"='no' AND "web_kit"='nightly build';