jexlParser does not support attribute access on object literals

[freshstrangemusic]

traverseAst will throw on the following expressions:

• {x: 1}.x
• [0][0] not a bug, unsupported syntax
• "'" Moved to jexlParser does not properly re-quote strings #228

[freshstrangemusic]

It turns out [0][0] is not valid JEXL.