Interesting. Copying the TinEye bookmarklet,

    javascript:void(window.open('http://tineye.com/search?pluginver=bookmark_1.0&url='%20+%20encodeURIComponent(document.URL)));

into the address bar did nothing; an "Error: uncaught exception: ReferenceError: window is not defined" was logged in the error console.

Clicking it as normal worked as expected, though.