Tests for history.pushState() URL rewriting

[domenic]

See whatwg/html#6836.

/cc @rakina

[domenic]

Summary of results for the scheme-based version versus current browsers:

• Firefox still gets the wrong exception a lot
• Firefox disallows rewriting blob URLs, but should allow rewriting them to themselves or hashed versions of themselves
• Firefox disallows rewriting about: URLs, but should allow rewriting them to themselves or hashed versions of themselves
• Firefox disallows rewriting data: URLs, but should allow rewriting them to themselves or hashed versions of themselves
• Chrome allows rewriting blob: URLs to new same-origin search or path, but should not
• Chrome allows rewriting data: URLs to a new search, but should not
• Chrome disallows rewriting about: URLs, but should allow rewriting them to themselves or hashed versions of themselves
• Chrome disallows rewriting the path of sandboxed URLs, but should allow it
• Safari allows rewriting blob: URLs to new same-origin search or path, but should not
• Safari allows rewriting data: URLs to a new search, but should not
• Safari disallows rewriting the path of sandboxed URLs, but should allow it