function getClosestInstanceFromNode(node) {
	  if (node[internalInstanceKey]) {
	    return node[internalInstanceKey];
	  }

	  // Walk up the tree until we find an ancestor whose instance we have cached.
	  var parents = [];
	  while (!node[internalInstanceKey]) {
	    parents.push(node);
	    if (node.parentNode) {
	      node = node.parentNode;
	    } else {
	      // Top of the tree. This node must not be part of a React tree (or is
	      // unmounted, potentially).
	      return null;
	    }
	  }

	  var closest;
	  var inst;
	  for (; node && (inst = node[internalInstanceKey]); node = parents.pop()) {
	    closest = inst;
	    if (parents.length) {
	      precacheChildNodes(inst, node);
	    }
	  }

	  return closest;
	}
Given a DOM node, return the closest ReactDOMComponent or
ReactDOMTextComponent instance ancestor.