src/core/document.js

import "array";

var d3_document = document,
    d3_documentElement = d3_document.documentElement,
    d3_window = window;

// Redefine d3_array if the browser doesn’t support slice-based conversion.
try {
  d3_array(d3_documentElement.childNodes)[0].nodeType;
} catch(e) {
  d3_array = function(list) {
    var i = list.length, array = new Array(i);
    while (i--) array[i] = list[i];
    return array;
  };
}