In IE8 'T' format in new Date results in Error when including es5-shim instead of Default Browser Behaviour of NAN

[smoothlikejazz]

Issue
In IE8 using the Date instance and executing a new date including the 'T' format results in an error outlined below when including the es5-shim.

* Sample*

<script src="es5-shim.js" type="text/javascript" charset="utf-8"></script>
<script type="text/javascript" charset="utf-8">
        console.log(new Date("2015-05-18T21:55:18Z"));
</script>

Results in Error
Object doesn't support this property or method es5-shim.js, line 926 character 21

Default Behaviour without Shim
Running the same sample above without the shim, IE8 will return NAN.

Context
In our current application we are handling NAN, the problem is that some third-party libraries are using new Date() and the error is occurring within the external library when including the es5-shim. So we isolated the issue in IE8 to be that of the new Date with 'T' format.

Conclusion
Were not sure why when including the es5-shim this fatal error is happening for IE8. but would like to request a patch or fix.

[ljharb]

Thanks, I definitely see this error. I'll see if I can investigate - I'm not sure what version of the es5-shim you're running - can you provide an example of what line 926 looks like, so I can map it to my version?

[smoothlikejazz]

Hey sure no problem, thanks for looking into, here is the snippet from my checked out version.

           var DateShim = function Date(Y, M, D, h, m, s, ms) {
                var length = arguments.length;
                if (this instanceof NativeDate) {
                    var date = length === 1 && String(Y) === Y ? // isString(Y) // --> Line 926
                        // We explicitly pass it through parse:
                        new NativeDate(Date.parse(Y)) :
                        // We have to manually make calls depending on argument
                        // length here
                        length >= 7 ? new NativeDate(Y, M, D, h, m, s, ms) :
                            length >= 6 ? new NativeDate(Y, M, D, h, m, s) :
                                length >= 5 ? new NativeDate(Y, M, D, h, m) :
                                    length >= 4 ? new NativeDate(Y, M, D, h) :
                                        length >= 3 ? new NativeDate(Y, M, D) :
                                            length >= 2 ? new NativeDate(Y, M) :
                                                length >= 1 ? new NativeDate(Y) :
                                                    new NativeDate();
                    // Prevent mixups with unfixed Date object
                    defineProperties(date, { constructor: Date }, true);
                    return date;
                }
                return NativeDate.apply(this, arguments);
            };

[ljharb]

And which of those lines is 926? I think we're off by 1-2 :-)

[smoothlikejazz]

For me it falls on this.

926: var date = length === 1 && String(Y) === Y ? // isString(Y)