Small optimisation in TerritoryLayer.renderLayer call to dedupe Date.… (#759)

## Description:

Small optimisation in TerritoryLayer.renderLayer call to dedupe
Date.now()

## Please complete the following:

- [-] I have added screenshots for all UI updates
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:

N/A

Co-authored-by: robertpitt <robertpitt1988@gmail.com>

src/client/graphics/layers/TerritoryLayer.ts

@@ -186,11 +186,12 @@ export class TerritoryLayer implements Layer {
   }
 
   renderLayer(context: CanvasRenderingContext2D) {
+    const now = Date.now();
     if (
-      Date.now() > this.lastDragTime + this.nodrawDragDuration &&
-      Date.now() > this.lastRefresh + this.refreshRate
+      now > this.lastDragTime + this.nodrawDragDuration &&
+      now > this.lastRefresh + this.refreshRate
     ) {
-      this.lastRefresh = Date.now();
+      this.lastRefresh = now;
       this.renderTerritory();
       this.context.putImageData(this.imageData, 0, 0);
     }