661923 - Warning spam when dismissing alert with 'esc': "WARNING: NS_ENSURE_TRUE(parentDocShell && treeItem != parentTreeItem) failed" & "WARNING: NS_ENSURE_TRUE(parentPresShell) failed:"

Status: NEW

(Core :: Layout, defect)

Description

[Daniel Holbert [:dholbert]]

Attachment: testcase

STEPS TO REPRODUCE:
 1. Load attached testcase in debug build.
 2. Click testcase.
 3. Hit Esc to cancel each alert.

ACTUAL RESULTS:
These two warnings are spammed to terminal, when the second and third alerts appear:
{
WARNING: NS_ENSURE_TRUE(parentDocShell && treeItem != parentTreeItem) failed: file layout/base/nsPresShell.cpp, line 6405
WARNING: NS_ENSURE_TRUE(parentPresShell) failed: file layout/base/nsPresShell.cpp, line 6423
}

Basically, it looks like we spam those warnings whenever one alert is canceled with Esc and another alert immediately replaces it.

Not sure at this point if these warnings actually indicate of something bad/unexpected.  If so, we should fix it.  If not, we should handle this condition in a less spammy way.