Revert "OrbitControls: Removed unused zoomChanged variable."

This reverts commit 0a97813fd293f77b7c2b5a5432a9224acd06926c.

examples/jsm/controls/OrbitControls.js

@@ -323,6 +323,7 @@ class OrbitControls extends EventDispatcher {
 
 		let scale = 1;
 		const panOffset = new Vector3();
+		let zoomChanged = false;
 
 		const rotateStart = new Vector2();
 		const rotateEnd = new Vector2();
@@ -454,6 +455,7 @@ class OrbitControls extends EventDispatcher {
 
 				scope.object.zoom = Math.max( scope.minZoom, Math.min( scope.maxZoom, scope.object.zoom * dollyScale ) );
 				scope.object.updateProjectionMatrix();
+				zoomChanged = true;
 
 			} else {
 
@@ -474,6 +476,7 @@ class OrbitControls extends EventDispatcher {
 
 				scope.object.zoom = Math.max( scope.minZoom, Math.min( scope.maxZoom, scope.object.zoom / dollyScale ) );
 				scope.object.updateProjectionMatrix();
+				zoomChanged = true;
 
 			} else {