Parse a CSS document.
The application can use this method to instruct the CSS parser to begin parsing an CSS document from any valid input source (a character stream, a byte stream, or a URI).
Applications may not invoke this method while a parse is in progress (they should create a new Parser instead for each additional CSS document). Once a parse is complete, an application may reuse the same Parser object, possibly with a different input source.
@param source The input source for the top-level of theCSS document.
@exception CSSException Any CSS exception, possiblywrapping another exception.
@exception java.io.IOException An IO exception from the parser,possibly from a byte stream or character stream supplied by the application.
@see InputSource
@see #parseStyleSheet(java.lang.String)
@see #setDocumentHandler
@see #setErrorHandler