Remove unused option for disabling IndexedDB

`createMatrixClient` and surrounding paths support an argument to disable
IndexedDB, but it is never actually used. This removes the option to simplify
the code.

src/MatrixClientPeg.js

@@ -171,7 +171,7 @@ class MatrixClientPeg {
         return matches[1];
     }
 
-    _createClient(creds: MatrixClientCreds, useIndexedDb) {
+    _createClient(creds: MatrixClientCreds) {
         const opts = {
             baseUrl: creds.homeserverUrl,
             idBaseUrl: creds.identityServerUrl,
@@ -183,7 +183,7 @@ class MatrixClientPeg {
             verificationMethods: [verificationMethods.SAS]
         };
 
-        this.matrixClient = createMatrixClient(opts, useIndexedDb);
+        this.matrixClient = createMatrixClient(opts);
 
         // we're going to add eventlisteners for each matrix event tile, so the
         // potential number of event listeners is quite high.

src/utils/createMatrixClient.js

@@ -32,23 +32,18 @@ try {
  * @param {Object} opts  options to pass to Matrix.createClient. This will be
  *    extended with `sessionStore` and `store` members.
  *
- * @param {bool} useIndexedDb True to attempt to use indexeddb, or false to force
- *     use of the memory store. Default: true.
- *
  * @property {string} indexedDbWorkerScript  Optional URL for a web worker script
  *    for IndexedDB store operations. By default, indexeddb ops are done on
  *    the main thread.
  *
  * @returns {MatrixClient} the newly-created MatrixClient
  */
-export default function createMatrixClient(opts, useIndexedDb) {
-    if (useIndexedDb === undefined) useIndexedDb = true;
-
+export default function createMatrixClient(opts) {
     const storeOpts = {
         useAuthorizationHeader: true,
     };
 
-    if (indexedDB && localStorage && useIndexedDb) {
+    if (indexedDB && localStorage) {
         storeOpts.store = new Matrix.IndexedDBStore({
             indexedDB: indexedDB,
             dbName: "riot-web-sync",
@@ -61,7 +56,7 @@ export default function createMatrixClient(opts, useIndexedDb) {
         storeOpts.sessionStore = new Matrix.WebStorageSessionStore(localStorage);
     }
 
-    if (indexedDB && useIndexedDb) {
+    if (indexedDB) {
         storeOpts.cryptoStore = new Matrix.IndexedDBCryptoStore(
             indexedDB, "matrix-js-sdk:crypto",
         );