Source

File: wp-includes/customize/class-wp-customize-cropped-image-control.php

public function to_json() {
		parent::to_json();

		$this->json['width']       = absint( $this->width );
		$this->json['height']      = absint( $this->height );
		$this->json['flex_width']  = absint( $this->flex_width );
		$this->json['flex_height'] = absint( $this->flex_height );
	}