test(browser): change mock location definition to use defineProperty

The original fix for which this mock location logic was written fixes
a bug in master which also exists in 1.2.x. Cherry-picking the fix
to the 1.2.x branch was difficult because the mock location object
used ES5 get/set syntax, which is not supported in IE8.

This fix changes the implementation to work with IE8 and modern
browsers.

IE8's defineProperty only works on certain types of objects, such as
DOM elements. So the mock location is a div element in this
implementation.