Normalize HTML Title Whitespace

[mookums]

This solves the failing WPT: html/dom/documents/dom-tree-accessors/document.title-03.html by ensuring that any whitespace subslices are replaced by a single space.

[karlseguin]

You might be able to do this without an allocator.

The web apis, i.e. set_title, can take a title: []u8 rather than a []const u8, so you could normalize it in-place.

That leaves documentHTMLParse, and the question becomes, can the dom_string you get from get_title be mutated and passed back to set_title?? Worst case you could use the netsurf arena to create the new string, i.e. c.dom_string_create