Remove dummy emscripten_set_offscreencanvas_size. NFC (#23279)

This is an internal-only API that is not directly callable by user code.

The only place that this function is called is from
`system/lib/html5/offscreencanvas.c` as a result of
`_emscripten_set_offscreencanvas_size_on_thread`.

Author: sbc100

src/library_html5.js

@@ -2297,8 +2297,6 @@ var LibraryHTML5 = {
   },
 
 #if OFFSCREENCANVAS_SUPPORT
-  _emscripten_set_offscreencanvas_size: 'emscripten_set_canvas_element_size',
-
   $setOffscreenCanvasSizeOnTargetThread__deps: ['$stringToNewUTF8', '_emscripten_set_offscreencanvas_size_on_thread'],
   $setOffscreenCanvasSizeOnTargetThread: (targetThread, targetCanvas, width, height) => {
     targetCanvas = targetCanvas ? UTF8ToString(targetCanvas) : '';
@@ -2414,15 +2412,6 @@ var LibraryHTML5 = {
   },
 #endif
 
-#if !PTHREADS || !OFFSCREENCANVAS_SUPPORT
-  _emscripten_set_offscreencanvas_size: (target, width, height) => {
-#if ASSERTIONS
-    err('emscripten_set_offscreencanvas_size: Build with -sOFFSCREENCANVAS_SUPPORT=1 to enable transferring canvases to pthreads.');
-#endif
-    return {{{ cDefs.EMSCRIPTEN_RESULT_NOT_SUPPORTED }}};
-  },
-#endif
-
   // JavaScript-friendly API, returns pair [width, height]
   $getCanvasElementSize__deps: ['emscripten_get_canvas_element_size', '$stackSave', '$stackRestore', '$stringToUTF8OnStack'],
   $getCanvasElementSize: (target) => {

src/library_sigs.js

@@ -327,7 +327,6 @@ sigs = {
   _emscripten_push_uncounted_main_loop_blocker__sig: 'vppp',
   _emscripten_receive_on_main_thread_js__sig: 'dippip',
   _emscripten_runtime_keepalive_clear__sig: 'v',
-  _emscripten_set_offscreencanvas_size__sig: 'ipii',
   _emscripten_system__sig: 'ip',
   _emscripten_thread_cleanup__sig: 'vp',
   _emscripten_thread_exit_joinable__sig: 'vp',

system/lib/html5/offscreencanvas.c

@@ -10,7 +10,7 @@ typedef struct set_cavas_size_t {
 
 static void do_set_size(void* arg) {
   set_cavas_size_t* args = (set_cavas_size_t*)arg;
-  _emscripten_set_offscreencanvas_size(args->target, args->width, args->height);
+  emscripten_set_canvas_element_size(args->target, args->width, args->height);
   free((char *) args->target);
   free(arg);
 }

system/lib/libc/emscripten_internal.h

@@ -139,8 +139,6 @@ size_t _emscripten_fetch_get_response_headers_length(int32_t fetchID);
 size_t _emscripten_fetch_get_response_headers(int32_t fetchID, char *dst, size_t dstSizeBytes);
 void emscripten_fetch_free(unsigned int);
 
-EMSCRIPTEN_RESULT _emscripten_set_offscreencanvas_size(const char *target, int width, int height);
-
 // Internal implementation function in JavaScript side that emscripten_create_wasm_worker() calls to
 // to perform the wasm worker creation.
 emscripten_wasm_worker_t _emscripten_create_wasm_worker(void *stackLowestAddress, uint32_t stackSize);