message: Add XmlHttpRequest handlers after open (some impls raise abort during open).
diff: @@ -235,6 +235,8 @@ export namespace Gateway {
  const path = this.generateOpenAPIPathForOperation(identifier, new HttpProtocol.OperationRequest(...parameters));
  const connection = this.generateConnectionForOperationRequest();
  + connection.open(this.supplyHttpVerbForOperation(identifier), path, true);
  +
  connection.addEventListener("load", () => {
  if (connection.status === 200)
  resolve(this.deserializeOperationResult(connection.responseText));
  @@ -245,7 +247,6 @@ export namespace Gateway {
  connection.addEventListener("error", () => reject(new IModelError(BentleyStatus.ERROR, "Connection error.")));
  connection.addEventListener("abort", () => reject(new IModelError(BentleyStatus.ERROR, "Connection aborted.")));
  - connection.open(this.supplyHttpVerbForOperation(identifier), path, true);
  this.setOperationRequestHeaders(connection);
  connection.send(this.serializeParametersForOperationRequest(identifier, ...parameters));
  } catch (e) {
  