[Extensions] Fix a test to also pass with load on demand

The test was "too strict" and covering only the "expected
failure" (greater than comparison) case. Now that we can run Crosswalk
loading extensions on demand, we can pass it properly (equal
comparison).

Once we enable the feature by default in Crosswalk we should make the
test "strict" again, covering only the equal comparison.
Merge pull request #974 from cmarcelo/fix-test-for-load-on-demand

[Extensions] Fix a test to also pass with load on demand