This does "ContainsNonBMPCodePoint(UTF16ToString(text))" without any allocations.

This is a clone of "utf8.DecodeRuneInString" that has been modified to decode using WTF-8 instead.

See "scripts/dataurl-escapes.html" for how this was derived.

Returns the shorter of either a base64-encoded or percent-escaped data URL.

From: http://boost.sourceforge.net/doc/html/boost/hash_combine.html.

This is used instead of Go's built-in "mime.TypeByExtension" function because that function is broken on Windows: https://github.com/golang/go/issues/32350.

The returned array will always be at least one element.

Does "UTF16ToString(text) == str" without a temporary allocation.

This provides an efficient way to join lots of big string and byte slices together.

Each call to "Enter(i)" doesn't start until "Leave(i-1)" is called.

Go's "sync.WaitGroup" is not thread-safe.