[Android] Add test case for size(), hasItemAt() and getItemAt().

This patch is to add test case for size(), hasItemAt() and getItemAt().
Load url and get history size, get item at specified index, compare them with the expected result.
Judge whether has item at specified index.
Sorry for that getItemAtOnUiThread(-1) will throw an exception in the code I use yesterday.
I'll updated it. thanks.