Make sure lazy loaded images display in printed PDFs

The CSS animation will never complete in print media so will not display
in PDF rendering. A note is added to explain this rule.

Bug: T220668
Change-Id: I82260fa4e18a13970243d3cb2fc585aefb3c1d09

resources/skins.minerva.base.styles/print/styles.less

@@ -1,4 +1,5 @@
 @import '../../../minerva.less/minerva.variables';
+@import '../../../minerva.less/minerva.mixins';
 
 @media print {
 	.noprint,
@@ -27,6 +28,11 @@
 
 	img {
 		max-width: 100%;
+
+		// Disable lazy loading transition animation for print media (T220668) so they display.
+		&.image-lazy-loaded {
+			.animation( none ) !important;
+		}
 	}
 }