preprocess_html-add-ie-edge-support.php

<?php
/**
 * Implements hook_preprocess_html().
 */
function mytheme_preprocess_html(&$variables) {

  // IE EDGE SUPPORT
  if (drupal_get_http_header('X-UA-Compatible') === NULL) {
    drupal_add_http_header('X-UA-Compatible', 'IE=edge,chrome=1');
  }
  
  $meta_ie_edge= array(
    '#type' => 'html_tag',
    '#tag' => 'meta',
    '#attributes' => array(
      'http-equiv' => 'X-UA-Compatible',
      'content' =>  'IE=edge,chrome=1',
    ),
    '#weight' => -99999,
  );
  // Add header meta tag for IE to head
  drupal_add_html_head($meta_ie_edge, 'meta_ie_edge');
}