We need to have one or more tests that confirm that it is possible to add array index keyed properties (for example, "1", "65536", "0", etc.) to the global object.
This is needed because WebIDL is trying to forbid this, yet there is nothing in the ES spec. that says that is allowable.
We should probably also check and make sure that non-array index number strings can also be used as properties on the global object. For example, "1.0", "-3", "3.33e10", etc.
Actually, WebIDL (actually HTML) says that its global object actually has a "length" properties and if it is non-0 some actual array-index properties.
The test should probably be that if "length" doesn't exist then it can be declared as a global var and also that array index properties can be added.