[Qt][WK2] REGRESSION, fix a failing API test in qmltests

[Qt][WK2] REGRESSION, fix a failing API test in qmltests
https://bugs.webkit.org/show_bug.cgi?id=82700

Patch by Marcelo Lira <marcelo.lira@openbossa.org> on 2012-05-21
Reviewed by Alexis Menard.

The value of a CSS font-family property is expected to have single
quotes when white space is present in its name, and no quotes otherwise.
Font family names returned by WebView.experimental.preferences never add quotes.

Since what matter to the test is only the identity of the font, an auxiliar
method to remove single quotes was added.

* UIProcess/API/qt/tests/qmltests/WebView/tst_preferences.qml:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@117812 268f45cc-cd09-0410-ab3c-d52691b4dbfc