Adding grid properties to syntax definition

[georgezzhang]

The syntax definition was missing some of the CSS grid properties, leading to wonky highlighting. I added all the properties from the list on the MDN article here, in reverse alphabetical like the existing properties:

https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Grid_Layout#CSS_properties

Here's the list of properties:

grid-template-columns
grid-template-rows
grid-template-areas
grid-template
grid-auto-columns
grid-auto-rows
grid-auto-flow
grid
grid-row-start
grid-column-start
grid-row-end
grid-column-end
grid-row
grid-column
grid-area
grid-row-gap
grid-column-gap
grid-gap

Let me know what you think!

[braver]

Thanks! It's a bit early days for this spec, but it doesn't hurt to add them now.