Tests for prefix search scoring.

For bug 52886.

Change-Id: I27794574ce1d7f421e3289ade2f358582433e54c
Fix suggestion tests.

They had a mistake causing them to fail when the feature still works.

Change-Id: I4d2743c48f558a38c86818dfee6703902ca60f7f
Merge "Tests for prefix search scoring."
Merge "Fix suggestion tests."