Revert "Merge pull request #5637 from williamkray/wreck/clean-thumbnail-changes"

This reverts commit 5c1b38a48c, reversing
changes made to ec4a39a694.

src/components/views/messages/MImageBody.js

@@ -362,7 +362,7 @@ export default class MImageBody extends React.Component {
         }
 
         // The maximum height of the thumbnail as it is rendered as an <img>
-        const maxHeight = Math.min(this.props.maxImageHeight || 240, infoHeight);
+        const maxHeight = Math.min(this.props.maxImageHeight || 600, infoHeight);
         // The maximum width of the thumbnail, as dictated by its natural
         // maximum height.
         const maxWidth = infoWidth * maxHeight / infoHeight;