Reland r179521: Cleanup deadcode in Rendering

This patch relands [1] after removing the listBoxSelectItem change which
was not deadcode after all [2]. A test is not included in this patch because
all but 100 layouttests are not run on our android builders. I manually
tested this patch and confirmed that it does not cause menu lists to crash.

[1] https://src.chromium.org/viewvc/blink?view=rev&revision=179521
[2] http://src.chromium.org/viewvc/blink?view=rev&rev=179989

BUG=402059

Review URL: https://codereview.chromium.org/471533004

git-svn-id: svn://svn.chromium.org/blink/trunk@180781 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Eliminate globalFlag usage from http security layout tests.

Tests that polled globalFlag were using it as a way to figure out when
another subframe had loaded. Instead of using globalFlag, those tests
have been rewritten to use a combination of the window load event (which
waits for all subframes to finish loading before firing), the iframe
load event (which also waits for all subframes), and postMessage when
a subframe can only start running its tests after the entire page is
loaded.

BUG=405846
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/494343003

git-svn-id: svn://svn.chromium.org/blink/trunk@180782 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: NetworkPanel: remove NetworkBaseCalculator.

This class has single descendant, so it is useless.

Also added JSDocs, and removed unused code.

BUG=

Review URL: https://codereview.chromium.org/484953004

git-svn-id: svn://svn.chromium.org/blink/trunk@180783 bbb929c8-8fbe-4397-9dbb-9b2b20218538