Bug 845010 - turn nsIDOMWindowUtils.getScrollbarWidth() into .getScrollbarSize(); r=roc

--HG--
rename : dom/tests/mochitest/general/file_domWindowUtils_scrollbarWidth.html => dom/tests/mochitest/general/file_domWindowUtils_scrollbarSize.html
rename : dom/tests/mochitest/general/test_domWindowUtils_scrollbarWidth.html => dom/tests/mochitest/general/test_domWindowUtils_scrollbarSize.html