fix scrollbar for RTL languages (#1150)

make the behavior same as before for both RTL and LTR languages

make solution use dynamic scrollbar size

as suggested in CR

app/js/message_composer.js

@@ -733,7 +733,15 @@ MessageComposer.prototype.setUpInput = function () {
   if (!Config.Mobile) {
     var sbWidth = getScrollWidth()
     if (sbWidth) {
-      (this.richTextareaEl || this.textareaEl).css({marginRight: -sbWidth})
+      // hide scrollbar for both LTR and RTL languages
+      // both scrollbars are hidden inside the paddings
+      // that are overflown outside of view
+      (this.richTextareaEl || this.textareaEl).css({
+        left: -sbWidth,
+        width: 'calc(100% + ' + (2 * sbWidth) + 'px)',
+        'padding-left': sbWidth + 2,
+        'padding-right': sbWidth + 28
+      })
     }
   }
 }

app/less/desktop.less

@@ -1154,11 +1154,13 @@ a.im_panel_peer_photo .peer_initials {
   box-shadow: none;
   outline: none;
   box-shadow: 0 1px 0 0 #e8e8e8;
-  padding: 1px 30px 1px 0;
+  padding: 1px 28px 1px 0;
+  position: relative;
   margin: 0;
   min-height: 50px;
   line-height: 20px;
   height: auto;
+  box-sizing: border-box;
 
   &:focus {
     border: 0;