Bug 936353: when confirming a pick from the camera, display the EXIF preview, not the full-size image
(cherry picked from commit 21d0c957a3bd47d1c4fdeb2c7c24fd7f1d11cb7a)
[v1.3] Bug 957545 - Disable test_dialer_add_contact because it's erroring on every ru
Bug 934429 - Remove layout/style reflows from the startup path r=rwaldron,julienw

- Do not lazy load CSS files as those trigger a reflow
- Do not read the height of the thread list container when starting up
Merge pull request #15113 from viorelaioia/bug_957545_1.3

[v1.3] Bug 957545 - Disable test_dialer_add_contact because it's erroring on every run
Merge pull request #14730 from davidflanagan/bug936353-v1.3

Bug 936353: when confirming a pick from the camera, display the EXIF preview r=wilsonpage