Add explicit GL dependency to library_html5_webgl

The dependency wrangling here was a workaround for a problem that was
solved in #16405 (see the command that is being deleted).

Pretty much all the functions in this depend either directly or
indirectly on the global GL object, so it makes sense to use autoAddDeps
rather than try to add individual deps.

Author: sbc100

src/library_html5_webgl.js

@@ -71,14 +71,7 @@ var LibraryHtml5WebGL = {
   emscripten_webgl_commit_frame: 'emscripten_webgl_do_commit_frame',
 #endif
 
-  // This code is called from emscripten_webgl_create_context() and proxied
-  // to the main thread when in offscreen framebuffer mode. This won't be
-  // called if GL is not linked in, but also make sure to not add a dep on
-  // GL unnecessarily from here, as that would cause a linker error.
   emscripten_webgl_do_create_context__deps: [
-#if LibraryManager.has('library_webgl.js')
-  '$GL',
-#endif
 #if USE_PTHREADS && OFFSCREEN_FRAMEBUFFER
   'emscripten_webgl_create_context_proxied',
 #endif
@@ -641,6 +634,10 @@ function handleWebGLProxying(funcs) {
 }
 
 handleWebGLProxying(LibraryHtml5WebGL);
+#endif // USE_PTHREADS
+
+#if LibraryManager.has('library_webgl.js')
+autoAddDeps(LibraryHtml5WebGL, '$GL');
 #endif
 
 mergeInto(LibraryManager.library, LibraryHtml5WebGL);