Instead of editing the template you could also try this:
<?php
/** Remove short description if product tabs are not displayed */
function dot_reorder_product_page() {
if ( get_option('woocommerce_product_tabs') == false ) {
remove_action( 'woocommerce_single_product_summary', 'woocommerce_template_single_excerpt', 20 );
}
}
add_action( 'woocommerce_before_main_content', 'dot_reorder_product_page' );
/** Display product description the_content */
function dot_do_product_desc() {
global $woocommerce, $post;
if ( $post->post_content ) : ?>
<div itemprop="description" class="item-description">
<?php $heading = apply_filters('woocommerce_product_description_heading', __('Product Description', 'woocommerce')); ?>
<!-- <h2><?php echo $heading; ?></h2> -->
<?php the_content(); ?>
</div>
<?php endif;
}
add_action( 'woocommerce_single_product_summary', 'dot_do_product_desc', 20 );