Update attribution_control.js (#8082)

* Update attribution_control.js

fix #8047

Update attribution_control.js

optimalization of fix

* Update attribution_control.js

change variable names String -> HTML
fix linter errors

* fix line endings lint errors

* fix fix fix!

fix === linter error, remove unwanted flow monitoring added by linter fix

src/ui/control/attribution_control.js

@@ -30,6 +30,7 @@ class AttributionControl {
     _container: HTMLElement;
     _innerContainer: HTMLElement;
     _editLink: ?HTMLAnchorElement;
+    _attribHTML: string;
     styleId: string;
     styleOwner: string;
 
@@ -157,8 +158,15 @@ class AttributionControl {
             }
             return true;
         });
+
+        // check if attribution string is different to minimize DOM changes
+        const attribHTML = attributions.join(' | ');
+        if (attribHTML === this._attribHTML) return;
+
+        this._attribHTML = attribHTML;
+
         if (attributions.length) {
-            this._innerContainer.innerHTML = attributions.join(' | ');
+            this._innerContainer.innerHTML = attribHTML;
             this._container.classList.remove('mapboxgl-attrib-empty');
         } else {
             this._container.classList.add('mapboxgl-attrib-empty');