Use CSS to resize the lightboxed image instead of Javascript

Summary: We can let the browser do the scaling with some simpler CSS rules.

Test Plan: Opened very large images in Safari, Firefox and Chrome and resized the browser. Observed smooth scaling and no issues with the image overlapping UI elements, etc.

Reviewers: btrahan, vrana

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1896

Differential Revision: https://secure.phabricator.com/D3802

webroot/rsrc/css/aphront/lightbox-attachment.css

@@ -19,7 +19,9 @@
 }
 
 .lightbox-attachment img {
-  margin: 50px auto 0;
+  margin: 3% auto 0;
+  max-height: 90%;
+  max-width: 90%;
 }
 
 .lightbox-attachment .loading {

webroot/rsrc/js/application/core/behavior-lightbox-attachments.js

@@ -4,7 +4,6 @@
  *           javelin-stratcom
  *           javelin-dom
  *           javelin-mask
- *           javelin-vector
  *           javelin-util
  */
 
@@ -233,37 +232,7 @@ JX.behavior('lightbox-attachments', function (config) {
       return;
     }
     var img = JX.DOM.find(lightbox, 'img');
-    var d   = JX.Vector.getDim(img);
-    JX.Stratcom.addData(img, { x : d.x, y : d.y } );
-
-    return resizeLightBox(e);
-  }
-
-  function resizeLightBox(e) {
-    if (!lightbox) {
-      return;
-    }
-    var img = JX.DOM.find(lightbox, 'img');
-    var v   = JX.Vector.getViewport();
-    var d   = JX.Stratcom.getData(img);
-
-    var w = d.x;
-    var h = d.y;
-    var scale = 0;
-    if (w > (v.x - x_margin)) {
-      scale = (v.x - x_margin) / w;
-      w = w * scale;
-      h = h * scale;
-    }
-    if (h > (v.y - y_margin)) {
-      scale = (v.y - y_margin) / h;
-      w = w * scale;
-      h = h * scale;
-    }
-
     JX.DOM.alterClass(img, 'loading', false);
-    JX.$V(w, h).setDim(img);
-    JX.Vector.getViewport().setDim(lightbox);
   }
 
   JX.Stratcom.listen(
@@ -272,12 +241,6 @@ JX.behavior('lightbox-attachments', function (config) {
     loadLightBox
   );
 
-  JX.Stratcom.listen(
-    'resize',
-    null,
-    resizeLightBox
-  );
-
   JX.Stratcom.listen(
     'keydown',
     null,