emscripten: Move fill-document from hint/property to a window flag.

Fixes #14617.

include/SDL3/SDL_hints.h

@@ -787,32 +787,6 @@ extern "C" {
  */
 #define SDL_HINT_EMSCRIPTEN_KEYBOARD_ELEMENT "SDL_EMSCRIPTEN_KEYBOARD_ELEMENT"
 
-/**
- * Dictate that windows on Emscripten will fill the whole browser window.
- *
- * When enabled, the canvas element fills the entire document. Resize events
- * will be generated as the browser window is resized, as that will adjust the
- * canvas size as well. The canvas will cover anything else on the page,
- * including any controls provided by Emscripten in its generated HTML file
- * (in fact, any elements on the page that aren't the canvas will be moved
- * into a hidden `div` element).
- *
- * Often times this is desirable for a browser-based game, but it means
- * several things that we expect of an SDL window on other platforms might not
- * work as expected, such as minimum window sizes and aspect ratios.
- *
- * This hint overrides SDL_PROP_WINDOW_CREATE_EMSCRIPTEN_FILL_DOCUMENT_BOOLEAN
- * properties when creating an SDL window.
- *
- * This hint only applies to the Emscripten platform.
- *
- * This hint can be set at any time (before creating the window, or to toggle
- * its state later). Only one window can fill the document at a time.
- *
- * \since This hint is available since SDL 3.4.0.
- */
-#define SDL_HINT_EMSCRIPTEN_FILL_DOCUMENT "SDL_EMSCRIPTEN_FILL_DOCUMENT"
-
 /**
  * A variable that controls whether the on-screen keyboard should be shown
  * when text input is active.