code: function getAllExpressionStatements(node) {
    console.assert(node.body && node.body.body);
    var expressionStatements = [];
    node.body.body.forEach(function(childNode) {
      if (childNode.type == 'ExpressionStatement') {
        expressionStatements.push(childNode);
      } else if (childNode.body) {
        var childExpressions = getAllExpressionStatements(childNode);
        expressionStatements.push.apply(expressionStatements, childExpressions);
      }
    });
    return expressionStatements;
  }
docs: Recursively find all expression statements in all block nodes.
  @param {ASTNode} node
  @return {!Array.<ASTNode>}