function isLiteral(ast) {
  return ast.body.length === 0 ||
      ast.body.length === 1 && (
      ast.body[0].expression.type === AST.Literal ||
      ast.body[0].expression.type === AST.ArrayExpression ||
      ast.body[0].expression.type === AST.ObjectExpression);
}
@name $$testability#findBindings

@description
Returns an array of elements that are bound (via ng-bind or {{}})
to expressions matching the input.

@param {Element} element The element root to search from.
@param {string} expression The binding expression to match.
@param {boolean} opt_exactMatch If true, only returns exact matches
    for the expression. Filters and whitespace are ignored.