The new JS::MarkupGenerator class can convert both a JS source string
and a JS Runtime Value into properly formatted HTML using the new
LibWeb System Palette css color values.
It makes more sense for this JS -> HTML process to occur in LibJS
so that it can be used elsewhere, namely Markdown code block syntax
highlighting. It also means the Browser can worry less about LibJS
implementation details.
This commit adds the following classes: SymbolObject, SymbolConstructor,
SymbolPrototype, and Symbol. This commit does not introduce any
new functionality to the Object class, so they cannot be used as
property keys in objects.
