function getTextContentAccessor() {
	  if (!contentKey && ExecutionEnvironment.canUseDOM) {
	    // Prefer textContent to innerText because many browsers support both but
	    // SVG <text> elements don't support innerText even when <div> does.
	    contentKey = 'textContent' in document.documentElement ? 'textContent' : 'innerText';
	  }
	  return contentKey;
	}
Gets the key used to access text content on a DOM node.

@return {?string} Key used to access text content.
@internal