Quote name of attribute to nested components

[fjorgemota]

This fixes #887 by quoting name of attributes if those are invalid JS identifiers when passing data to nested components, so something like this would compile and run successfully.

Please note that this does not add support for acessing these attributes directly on the component code, but only adds support for passing that data to the nested component. I think a valid idea here is to let the user use a computed property on the nested component returning the whole state (like state, maybe?) to access the data on template tags using { state["b-c"] }, for example.

I'll add tests tonight, by the way, so this is still a WIP. But feel free to test and comment about the idea. =)

[fjorgemota]

Ok, I added a few tests of what I was thinking about the support to invalid JS identifiers as attributes to nested components.

Please note that I did not add support for the usage of invalid JS attributes on any other place than bind: and attributes passed to nested components. So, for example, we cannot use {b-c} or bind:x='b-c', for example, which for me is a bit confusing, but I do not see it as a problem when considering ONLY the original issue.

I'll remove the WIP flag (as this PR already has tests included), but really feel free to comment on the "solution" to the issue. Thanks for the great project, by the way. :)

[Rich-Harris]

thank you! released 2.9.0 with the fix

[fjorgemota]

Thank you! :D