FileStructure.BOMGarbageData -- loadVtt is asserting 0 cues rather than parse failure.

C++ compiler is confused, because 'bool' can be implicitly converted to 'int', and we have a version of loadVtt which takes a string and an integer (expectedNumCues). So what's happening is it's reading this as "we expect 0 cues", rather than "we expect parsing to fail"

```C++
TEST_F(FileStructure, BOMGarbageData)
{
  loadVtt( "filestructure/bom_garbage_data.vtt", false );
  ASSERT_EQ(1, errorCount()) << "This file should fail the test because it has garbage data";
  assertEquals( getError( 0 ), WEBVTT_MALFORMED_TAG, 1, 1 );
}
```