Bug 1373293: Follow-up: Bump StartupCache schema version. r=trivial

MozReview-Commit-ID: JR1ZP9ByRFb

toolkit/components/extensions/ExtensionParent.jsm

@@ -1243,7 +1243,7 @@ let IconDetails = {
 let StartupCache = {
   DB_NAME: "ExtensionStartupCache",
 
-  SCHEMA_VERSION: 3,
+  SCHEMA_VERSION: 4,
 
   STORE_NAMES: Object.freeze(["locales", "manifests", "schemas"]),