parseWith method
Implementation
Statement parseWith() {
int start = token?.startOffset??0;
int line = token?.line??0;
assert(token?.text == 'with');
consume(Token.NAME);
consume(Token.LPAREN);
Expression exp = parseExpression();
consume(Token.RPAREN);
Statement body = parseStatement();
return new WithStatement(exp, body)
..start = start
..end = endOffset
..line = line;
}