Fix another source of flakiness in ErrorPageTest

Fix another source of flakiness in ErrorPageTest

We need to wait for correct number of navigations when going back or forward
to the LinkDoctor page.

Re-enable previously disabled tests and remove the now-duplicate browser test.

The test is still not very solid, because the LinkDoctor should be mocked.

TEST=Covered by ui_tests.
http://crbug.com/19361, http://crbug.com/19395

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=24446

[huanr, 2009-08-25 20:54:37]

LGTM

http://codereview.chromium.org/174396/diff/1/5
File chrome/browser/errorpage_uitest.cc (right):

http://codereview.chromium.org/174396/diff/1/5#newcode65
Line 65: GetActiveTab()->GoBackBlockUntilNavigationsComplete(2);
please add a comment to explain the number of navigation being 2.