Update ExporterTest::testShortenedExportForMultibyteCharacters() to use trimNewline()

tests/ExporterTest.php

@@ -313,7 +313,7 @@ EOF;
         try {
             $this->assertSame(
               "'いろはにほへとちりぬるをわかよたれそつねならむうゐのおくや...しゑひもせす'",
-              $this->trimnl($this->exporter->shortenedExport('いろはにほへとちりぬるをわかよたれそつねならむうゐのおくやまけふこえてあさきゆめみしゑひもせす'))
+              $this->trimNewline($this->exporter->shortenedExport('いろはにほへとちりぬるをわかよたれそつねならむうゐのおくやまけふこえてあさきゆめみしゑひもせす'))
             );
         } catch (\Exception $e) {
             mb_internal_encoding($oldMbInternalEncoding);