Fix resource extraction issue
The change in MR !27 (merged) caused a broken classpath for org.eclipse.set.browser.cef, as both org.eclipse.browser (bundle) and org.eclipse.browser.cef (bundle).
Oddly this worked from within Eclipse, but not if the browser is added externally (e.g. from the target platform). This MR resolves that issue. It also resolves resources being added twice.