ArcanistLintEngine::getLineAndCharFromOffset(string, integer) returns the wrong values for offsets in my test file.

Reproduction steps:

1. Make an ArcanistLintEngine object
2. list($line, $char) = $engine->getLineAndCharFromOffset('path/to/project.pbxproj', 13413);

Expected result:

• $line === 221, $char === 0

Actual result:

• $line === 220, $char === 5