Do not use the workaround for desktop nvidia on mobile and html5.

core/message_queue.cpp

@@ -271,7 +271,7 @@ void MessageQueue::flush() {
 	//using reverse locking strategy
 	_THREAD_SAFE_LOCK_
 
-	ERR_FAIL_COND(flushing);
+	ERR_FAIL_COND(flushing); //already flushing, you did something odd
 	flushing = true;
 
 	while (read_pos < buffer_end) {

drivers/gles2/rasterizer_canvas_gles2.cpp

@@ -456,7 +456,8 @@ void RasterizerCanvasGLES2::_canvas_item_render_commands(Item *p_item, Item *cur
 				glDisableVertexAttribArray(VS::ARRAY_COLOR);
 				glVertexAttrib4fv(VS::ARRAY_COLOR, r->modulate.components);
 
-#if 1
+//use a more compatible workaround, as this does not fail on nvidia
+#ifdef GLES_OVER_GL
 				//more compatible
 				state.canvas_shader.set_conditional(CanvasShaderGLES2::USE_TEXTURE_RECT, false);