On what Surface was the match with a Score of 6–4, 6–3 and Runner-up Outcome played?
CREATE TABLE "doubles_11_6_5" (
  "outcome" text,
  "date" text,
  "tournament" text,
  "surface" text,
  "partner" text,
  "opponents" text,
  "score" text
);
SELECT "surface" FROM "doubles_11_6_5" WHERE "outcome"='runner-up' AND "score"='6–4, 6–3';