reportOffset method
Reports a violation at the character offset of the file, described
by message.
Implementation
void reportOffset(int offset, String message) {
final CharacterLocation location = file.lineInfo.getLocation(offset);
violations.add(
StyleViolation(
ruleId: ruleId,
path: file.path,
line: location.lineNumber,
column: location.columnNumber,
message: message,
),
);
}