[GLUT/GLFW] Stop resizing canvas to 1x1 on exit/termination (#27833)

In 2012, `Module["canvas"].width = Module["canvas"].height = 1` was
added to the GLUT exit handler in `libglut.js` (#357) to simulate
closing the window when a GLUT program calls `exit()`.

When `libglfw.js` was created in 2013 (#1006), it was copied from
`libglut.js` as a template along with the `atexit` handler in
`glfwInit`, which was later moved into `glfwTerminate` when GLFW 3
support was added in 2014 (#1887).

Remove this 1x1 canvas resize from both libraries:
- Neither SDL1, SDL2, nor EGL resizes the canvas to 1x1 on shutdown or
exit.
- Calling `glfwInit()` followed by `glfwTerminate()` (even without
creating a window) unexpectedly clobbers the canvas dimensions.
- Resizing the canvas clears its bitmap, which destroys rendered output
if an application renders a static frame and then calls
`glfwTerminate()` or exits with `EXIT_RUNTIME=1`.
- In GLFW HiDPI mode, inline CSS dimensions remain set on the canvas, so
setting `width` and `height` to 1 only shrinks the backing buffer while
leaving the element at its previous CSS size.

Author: sbc100

src/lib/libglfw.js

@@ -1501,7 +1501,6 @@ var LibraryGLFW = {
     if (GLFW.devicePixelRatioMQL)
       GLFW.devicePixelRatioMQL.removeEventListener('change', GLFW.onDevicePixelRatioChange);
 
-    canvas.width = canvas.height = 1;
     GLFW.windows = null;
     GLFW.active = null;
   },

src/lib/libglut.js

@@ -370,9 +370,6 @@ var LibraryGLUT = {
       window.removeEventListener('DOMMouseScroll', GLUT.onMouseWheel, true);
 
       window.removeEventListener('resize', GLUT.onResize, true);
-
-      var canvas = Browser.getCanvas();
-      canvas.width = canvas.height = 1;
     });
   },
 

test/codesize/test_codesize_hello_dylink_all.json

@@ -1,7 +1,7 @@
 {
-  "a.out.js": 271910,
+  "a.out.js": 271876,
   "a.out.nodebug.wasm": 587923,
-  "total": 859833,
+  "total": 859799,
   "sent": [
     "IMG_Init",
     "IMG_Load",