Bug 569744 - Delayed loading of service.js causes test failures [r=Mardak]

Have FakeCryptoService.generateRandomIV() return 24 bytes so that Weave.Service._checkCrypto() believes it's the real deal. Fix undeclared variable.

services/sync/tests/unit/head_helpers.js

@@ -240,7 +240,8 @@ FakeCryptoService.prototype = {
   },
 
   generateRandomIV: function() {
-    return "fake-random-iv";
+    // A base64-encoded IV is 24 characters long
+    return "fake-fake-fake-random-iv";
   },
 
   generateRandomBytes: function(aByteCount) {

services/sync/tests/unit/test_syncengine_sync.js

@@ -274,7 +274,7 @@ function test_syncStartup_metaGet404() {
     do_check_eq(collection.wbos.scotsman.payload, undefined);
 
     _("New bulk key was uploaded");
-    key = crypto_steam.data.keyring["http://localhost:8080/1.0/foo/storage/keys/pubkey"];
+    let key = crypto_steam.data.keyring["http://localhost:8080/1.0/foo/storage/keys/pubkey"];
     do_check_eq(key.wrapped, "fake-symmetric-key-0");
     do_check_eq(key.hmac, "fake-symmetric-key-0                                            ");