Update svelte-jsx.d.ts (#408)

* Update svelte-jsx.d.ts

Adding missing type definitions for on:intro and on:outro start and end events.

```
Type '{ onoutrostart: () => boolean; onoutroend: () => boolean; class: string; }' is not assignable to type 'HTMLProps<HTMLDivElement>'.
  Property 'onoutrostart' does not exist on type 'HTMLProps<HTMLDivElement>'.ts(2322)
```

* Update svelte-jsx.d.ts

* Update svelte-jsx.d.ts

separated event types with vanilla dom comment

* Update svelte-jsx.d.ts

* ran yarn lint --fix

packages/svelte2tsx/svelte-jsx.d.ts

@@ -199,6 +199,12 @@
       // Transition Events
       ontransitionend?: TransitionEventHandler<T>;
 
+      // Svelte Transition Events
+      onoutrostart?: EventHandler<CustomEvent<null>, T>;
+      onoutroend?: EventHandler<CustomEvent<null>, T>;
+      onintrostart?: EventHandler<CustomEvent<null>, T>;
+      onintroend?: EventHandler<CustomEvent<null>, T>;
+
       // Message Events
       onmessage?: MessageEventHandler<T>;
       onmessageerror?: MessageEventHandler<T>;