ui-sref incorrectly adds state parameters to urls when current state has those parameters

[TimothyKrell]

Problem: ui-sref="route1" will incorrectly generate a url of href="route1?param1=something&param2=somethingelse"

Steps to reproduce:

1. Define a state with search parameters (url: 'route1?param1&param2')
2. Use ui-sref to define two links, one to just /route1 (ui-sref="route1") and one to /route1?param1=something&param2=somethingelse (ui-sref="route1({ param1: 'something', param2: 'somethingelse' }))
3. browse to /route1. Everything is as expected. ui-sref="route1" generates /route1 and ui-sref="route1({ param1: 'something', param2: 'somethingelse' }) generates /route1?param1=something&param2=somethingelse
4. browse to /route1?param1=something&param2=somethingelse. Both ui-sref directives generate a url of /route1?param1=something&param2=somethingelse. This is not expected and problematic. The first ui-sref (ui-sref="route1") should still generate a url of /route1

Here is a plunker demonstrating the problem.

[nateabele]

See #504.

[TimothyKrell]

Ah! Sorry. I looked before I submitted, but I guess I didn't search hard enough.