Remove redundant code

game.js

@@ -142,6 +142,9 @@ function stop_timing() {
 function restart_game() {
     game_finished = false;
     mines_placed = false;
+    // Based on the level, we calculate the grid size and amount
+    // of mines. The height of the grid increases every two
+    // levels.
     field_height = 8 + Math.floor(current_level / 2);
     minefield_initialize();
     update_particle_canvas_size();
@@ -157,11 +160,6 @@ function restart_game() {
 }
 
 function start_or_continue_game(level) {
-    // Based on the level, we calculate the grid size and amount
-    // of mines. The height of the grid increases every two
-    // levels.
-    current_level = level;
-    field_height = 8 + Math.floor(current_level / 2);
     let minefield_html = localStorage.getItem(current_level + "-minefield_html");
     $("#level").innerText = current_level;
     if (minefield_html == null) {
@@ -346,4 +344,4 @@ function lose_game() {
             cell.innerText = "";
         }
     });
-}
+}