The World of Color fastpass distribution for resort guest has changed. Previously, resort guests would enter California Adventure at 9AM and get fastpasses from the machines at Grizzly Rapids (and often immediately return to the hotel).
We lined up at the Grand Californian entrance to California Adventure at 8:30 (after already doing
Disneyland Magic Morning). We were second in line, so showing up at 9AM would have been fine. At 9AM, cast members walked down the line and handed out World of Color fastpasses -- they did not check for park tickets or room keys. This is a much more efficient process, taking only a few minutes.
The entrance opened at 9:30, and we were able to ride Little Mermaid 4 times

The park main gates also open at 9:30, but a room key is required to ride the Little Mermaid before 10AM. On our 3rd and 4th rides of Little Mermaid there were hundreds of non-resort guests waiting, but we were able to literally "walk on" the ride.