Consider converting attributes with dashes into to camelCased properties

[sorvell]

If an attribute is setup for a custom element that has a dash ('-') in it, it's reflected to a property with the same name. This makes referencing the value cumbersome since this['..'] notation must be used. Additionally, the property cannot be used as a binding value for mdv.

We could document that attributes with dashes are not supported.

However, we may want to convert these attributes to camelCased properties: an attribute "foo-bar" to a property "fooBar."

See feedback in https://groups.google.com/forum/#!topic/polymer-dev/GWzc8zekb-o

cc @ebidel

[michaelsbradleyjr]

+1 for auto-conversion or some workaround that allows attributes with dashes while preserving mdv binding and the firing of ..Changed methods.

[dfreedm]

If we have auto camelCased properties, maybe #142 should be supported by this mechanism as well?

[sorvell]

Dup of #150

[kaleb]

It took me a lot of debugging to realize that this was not supported.