Revert "Removed unnecessary try/catch from isInstanceOf"

This reverts commit 58ee52ad4a0ebf51f9add9b99188968268ed6f8e.

As it turns out, IE9 allows use of instanceof with special object types, not
just functions. One such example is HTMLElement; its type is `object', whereas
in Firefox and Chromium it is `function'. There is no reliable way to perform
this detection.

Therefore, the try/catch here is more reliable.