code: function isPartOfDirectivePrologue(node) {
  			var block = node.parent.parent;
  
  			if (block.type !== "Program" && (block.type !== "BlockStatement" || !FUNCTION_TYPE.test(block.parent.type))) {
  				return false;
  			}
  
  			// Check the node is at a prologue.
  			for (var i = 0; i < block.body.length; ++i) {
  				var statement = block.body[i];
  
  				if (statement === node.parent) {
  					return true;
  				}
  				if (!isDirective(statement)) {
  					break;
  				}
  			}
  
  			return false;
  		}
docs: Checks whether or not a given node is a part of directive prologues.
  See also: http://www.ecma-international.org/ecma-262/6.0/#sec-directive-prologues-and-the-use-strict-directive
  @param {ASTNode} node - A node to check.
  @returns {boolean} Whether or not the node is a part of directive prologues.
  @private