Fix sound playing from replaced WebM thumbnails in previewed/inlined quotes.

src/General/lib/clone.class

@@ -61,6 +61,8 @@ class Clone extends Post
       @file.thumb = $ '.fileThumb > [data-md5]', file
       @file.fullImage = $ '.full-image', file
 
+      @file.thumb.muted = true if @file.videoThumb
+
       # Contract thumbnails in quote preview
       ImageExpand.contract @ if contractThumb
 

src/Images/ImageLoader.coffee

@@ -50,6 +50,7 @@ ImageLoader =
       poster:      thumb.src
       textContent: thumb.alt
       className:   thumb.className
+    video.setAttribute 'muted', 'muted'
     video.dataset.md5 = thumb.dataset.md5
     video.style[attr] = thumb.style[attr] for attr in ['height', 'width', 'maxHeight', 'maxWidth']
     video.src         = file.URL