Bug 1388946 Part 2 Disable legacy extensions by default r=kmag

Also bump the xpi database schema version to force compatibility
recomputation (since we're not changing the application version number)

MozReview-Commit-ID: vVFIWmtN5v

--HG--
extra : rebase_source : 6e3e9a534aa390887573e538fa0bf14dd05dca50

browser/app/profile/firefox.js

@@ -1566,6 +1566,8 @@ pref("extensions.interposition.prefetching", true);
 pref("extensions.allow-non-mpc-extensions", false);
 #endif
 
+pref("extensions.legacy.enabled", false);
+
 // Enable blocking of e10s and e10s-multi for add-on users on beta/release.
 #if defined(RELEASE_OR_BETA) && !defined(MOZ_DEV_EDITION)
 pref("extensions.e10sBlocksEnabling", true);

toolkit/mozapps/extensions/internal/XPIProvider.jsm

@@ -189,7 +189,7 @@ const TOOLKIT_ID                      = "toolkit@mozilla.org";
 
 const XPI_SIGNATURE_CHECK_PERIOD      = 24 * 60 * 60;
 
-XPCOMUtils.defineConstant(this, "DB_SCHEMA", 22);
+XPCOMUtils.defineConstant(this, "DB_SCHEMA", 23);
 
 XPCOMUtils.defineLazyPreferenceGetter(this, "ALLOW_NON_MPC", PREF_ALLOW_NON_MPC);