annotated: quotes are not preserved

[bzz]

Discovered in bblfsh/javascript-driver#81 (comment) and as noted at bblfsh/javascript-driver#81 (comment) - this driver does not handle string literals in annotated mode the same way as other drivers do: it does not preserve the " and ' as part of the literal value in annotated mode.

On

<?php

"b\nc";
'b\ncq';

Actual

//*[@role='String' and @role='Literal'] XPath query results in

"@token":"b\nc","@type":"Scalar_String","attributes":{"kind":2}
"@token":"b\\ncq","@type":"Scalar_String","attributes":{"kind":1}

Expected

For annotated mode, @token values should be

'b\\ncq'
\"b\\ncq\"