[MSHTML] Fix 3 MSVC warnings about HTML*Element_handle_event()

- "...\htmlanchor.c(769) : warning C4028: formal parameter 2 different from declaration"
- "...\htmlarea.c(427) : warning C4028: formal parameter 2 different from declaration"
- "...\htmlform.c(757) : warning C4028: formal parameter 2 different from declaration"

Cherry-pick Jacek Caban https://source.winehq.org/git/wine.git/commit/a660f673cb7d6d04e0f2a9a98cff439b5403365b
CORE-7538

dll/win32/mshtml/htmlanchor.c

···
     return HTMLElement_QI(&This->element.node, riid, ppv);
 }
 
-static HRESULT HTMLAnchorElement_handle_event(HTMLDOMNode *iface, eventid_t eid, nsIDOMEvent *event, BOOL *prevent_default)
+static HRESULT HTMLAnchorElement_handle_event(HTMLDOMNode *iface, DWORD eid, nsIDOMEvent *event, BOOL *prevent_default)
 {
     HTMLAnchorElement *This = impl_from_HTMLDOMNode(iface);
     nsAString href_str, target_str;

dll/win32/mshtml/htmlarea.c

···
     return S_OK;
 }
 
-static HRESULT HTMLAreaElement_handle_event(HTMLDOMNode *iface, eventid_t eid, nsIDOMEvent *event, BOOL *prevent_default)
+static HRESULT HTMLAreaElement_handle_event(HTMLDOMNode *iface, DWORD eid, nsIDOMEvent *event, BOOL *prevent_default)
 {
     HTMLAreaElement *This = impl_from_HTMLDOMNode(iface);
     nsAString href_str, target_str;

dll/win32/mshtml/htmlform.c

···
     return S_OK;
 }
 
-static HRESULT HTMLFormElement_handle_event(HTMLDOMNode *iface, eventid_t eid, nsIDOMEvent *event, BOOL *prevent_default)
+static HRESULT HTMLFormElement_handle_event(HTMLDOMNode *iface, DWORD eid, nsIDOMEvent *event, BOOL *prevent_default)
 {
     HTMLFormElement *This = impl_from_HTMLDOMNode(iface);