15.3.4.5-15-5.js does not appear to make sense

[JosephPecoraro]

Test: test/built-ins/Function/prototype/bind/15.3.4.5-15-5.js

The test at a78650fde is currently:

/*---
es5id: 15.3.4.5-15-5
description: >
    Function.prototype.bind - The [[Configurable]] attribute of length
    property in F set as false
---*/

        var canConfigurable = false;
        var hasProperty = false;
        function foo() { }
        var obj = foo.bind({});
        hasProperty = obj.hasOwnProperty("length");
        delete obj.caller;
        canConfigurable = !obj.hasOwnProperty("length");

assert(hasProperty, 'hasProperty !== true');
assert.sameValue(canConfigurable, false, 'canConfigurable');

There are a number of pieces that don't seem to make sense:

1. The comment says [[Configurable]] should be false. The spec says [[Configurable]] should be true:
   https://tc39.github.io/ecma262/#sec-function.prototype.bind

   8. Perform ! DefinePropertyOrThrow(F, "length", PropertyDescriptor {[[Value]]: L, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true}).

2. The test is performing delete obj.caller, and not doing anything with the length property. Is caller somehow related to length? I suspect this should be delete obj.length.