Material: don't export attenuationDistance when it's set to the default value of Infinity (Fix #24797) (#24798)

src/materials/Material.js

@@ -300,7 +300,7 @@ class Material extends EventDispatcher {
 		if ( this.transmissionMap && this.transmissionMap.isTexture ) data.transmissionMap = this.transmissionMap.toJSON( meta ).uuid;
 		if ( this.thickness !== undefined ) data.thickness = this.thickness;
 		if ( this.thicknessMap && this.thicknessMap.isTexture ) data.thicknessMap = this.thicknessMap.toJSON( meta ).uuid;
-		if ( this.attenuationDistance !== undefined ) data.attenuationDistance = this.attenuationDistance;
+		if ( this.attenuationDistance !== undefined && this.attenuationDistance !== Infinity ) data.attenuationDistance = this.attenuationDistance;
 		if ( this.attenuationColor !== undefined ) data.attenuationColor = this.attenuationColor.getHex();
 
 		if ( this.size !== undefined ) data.size = this.size;