Fix spelling of 'attachment' in comments.

im/content/blist.js

@@ -520,7 +520,7 @@ var buddyList = {
       if (!("TextboxSpellChecker" in window))
         Components.utils.import("resource:///modules/imTextboxUtils.jsm");
       TextboxSpellChecker.registerTextbox(elt);
-      // force binding attachmant by forcing layout
+      // force binding attachment by forcing layout
       elt.getBoundingClientRect();
       elt.select();
     }
@@ -613,7 +613,7 @@ var buddyList = {
         elt.removeAttribute("value");
       elt.addEventListener("keypress", this.displayNameKeyPress);
       elt.addEventListener("blur", this.displayNameBlur);
-      // force binding attachmant by forcing layout
+      // force binding attachment by forcing layout
       elt.getBoundingClientRect();
       elt.select();
     }

im/content/contact.xml

@@ -299,7 +299,7 @@
         this.setAttribute("aliasing", "true");
         let textbox =
           document.getAnonymousElementByAttribute(this, "anonid", "displayname");
-        textbox.getBoundingClientRect(); // force binding attachmant by forcing layout
+        textbox.getBoundingClientRect(); // force binding attachment by forcing layout
         textbox.select();
 
         // Some keys (home/end for example) can make the selected item

im/content/conversation.xml

@@ -1553,7 +1553,7 @@
           elt.addEventListener("keypress", this._topicKeyPress);
           this._topicBlur = this.topicBlur.bind(this);
           elt.addEventListener("blur", this._topicBlur);
-          // force binding attachmant by forcing layout
+          // force binding attachment by forcing layout
           elt.getBoundingClientRect();
           if (this.hasAttribute("noTopic"))
             elt.value = "";