Regarding commit b9014d21caea4d8fe98c94c1fe6158b65db5db53 by Milian (use IDocument for mimetype query when available)

[David Nolden]

commit b9014d21caea4d8fe98c94c1fe6158b65db5db53
Author: Milian Wolff <mail at milianw.de>
Date:   Fri Jun 10 15:09:11 2011 +0200

    use IDocument for mimetype query when available in language controller

    this way we get proper language support when opening files without extension
    like e.g. <memory> or similar system headers. Furthermore there
are scripting
    languages that use the shebang instead of the extension to
advertise their mimetype


The idea is good, but it is not thread-safe to call documentForUrl,
while languageForUrl can be called from any thread. This patch can
thus lead to random crashes I think..

A better solution would be: When opening a document, force the
language-controller to cache its type, or something like that.