Bug 995605 - [Sora][Message][MMS]Can't add the text in content when forward a media MMS r=schung

The issue is that in compose.js, "pointer-events: none" is added after it's
removed, in this case.

This patch ensures that SMIL.parse always calls the callback in an asynchronous way,
so that the caller does not have any surprise.
Merge branch 'v1.3' into v1.3t
Bug 998118 - Dont display crashed background tabs. r=benfrancis
Bug 1001724: don't display EXIF preview images if aspect ratio does not match

media frame changes to use #-moz-samplesize if the exif preview is no good

set a maximum size for MediaFrame so photos are downsampled even when previewed in the camera

specify a maximum image size for all MediaFrame objects so large JPEGs can be previewed

use cropResizeRotate in the gallery metadata parser to improve thumbnail generation efficiency

fix failing test, add new media frame tests, remove logging statements