Fix dispatcher import to be extension agnostic

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/vector/platform/WebPlatform.js

@@ -19,7 +19,7 @@ limitations under the License.
 
 import VectorBasePlatform, {updateCheckStatusEnum} from './VectorBasePlatform';
 import request from 'browser-request';
-import dis from 'matrix-react-sdk/src/dispatcher.js';
+import dis from 'matrix-react-sdk/src/dispatcher';
 import { _t } from 'matrix-react-sdk/src/languageHandler';
 
 import url from 'url';