Lets set some points clear here.
1. China does not need to throw the first punch so to speak, it is not desperate nor is it in any rush because as things are going now, China is gaining more and more control through non-violent means. Philippines on the other hand, is not in a good position, if they don't take action fast, they will gradually loose all their footings in the SCS so they are desperately begging the world for help against a threat that they themselves escalated. So far, everyone is basically giving the Philippines the middle finger.
2. Even if China did attack the Philippines first (even though there's no need at all) and wipes out the Filipino military, why would any nation decide it would be prime time to attack China? Did a coalition of nations decide to attack Russia when they attacked Crimea, did a coalition of nations decide to attack the USA when they attack Iraq? Why would a coalition of nations suddenly attack China for the Philippines?
3. Definitely not like Japan in ww2 in anyway. Japan was a born imperialist empire, spreading beyond their means, and today is dwarfed by an industrial mega giant China. You talk about a coalition of nations will come to attack China like it will be the start of world war 3 then we'd let the thermos fly, but of course, USA attacking Iraq did not start a world war, doubtful attacking Philippines will either.