Bug 973407 - [Messages] Reduce reflows when element heights are updated

1. remove updateElementsHeight() call in messageComposerInputHandler(),
since updateSubjectHeight() already calls it

2. in cancelEdit(), only call updateElementsHeight() if in edit mode

3. in updateElementsHeight(), move code to set input width to 'auto' up
to avoid extra reflow if layout has changed prior to call

Added unit tests for cancelEdit().
Bug 972245 - Photos can appear distorted in the call log and in the SMS app(SMS part) r=julien
Merge pull request #16379 from yor-mozilla-com/fix973407

Bug 973407 - [Messages] Reduce reflows when element heights are updated r=julien
Revert "Merge pull request #16435 from evanxd/bug-973876"

This reverts commit 447eb65ee5a7428e3959ac3b1c0a3fbbfc125d43, reversing
changes made to 6894b915ee7d031a1f0ed16c422c48f293de1b84.
Bug 975298 - [email/backend] intermittent GELAM test failure for POP3 in test_account_bad_password_error. r=mcav

Land the results of the GELAM fix from
https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/285
into gaia.  The test fix involved adding additional logging and we want
/ need that logging propagated.
Merge pull request #16545 from asutherland/fixtest-pop3-badpwd

Bug 975298 - [email/backend] intermittent GELAM test failure for POP3 in test_account_bad_password_error. r=mcav