Fix typo in impress.js

transtion -> transition

src/impress.js

@@ -776,7 +776,7 @@
             // scrolling to element in hash.
             //
             // And it has to be set after animation finishes, because in Chrome it
-            // makes transtion laggy.
+            // makes transition laggy.
             // BUG: http://code.google.com/p/chromium/issues/detail?id=62820
             lib.gc.addEventListener( root, "impress:stepenter", function( event ) {
                 window.location.hash = lastHash = "#/" + event.target.id;