Builds are neccesary, even if you can spell necessary, and even in a CLOSED TREE

content/base/public/nsIContent.h

@@ -404,7 +404,7 @@ public:
    * @returns The name at the given index, or null if the index is
    *          out-of-bounds.
    * @note    The document returned by NodeInfo()->GetDocument() (if one is
-   *          present) is *not* neccesarily the owner document of the element.
+   *          present) is *not* necessarily the owner document of the element.
    * @note    The pointer returned by this function is only valid until the
    *          next call of either GetAttrNameAt or SetAttr on the element.
    */

content/base/src/nsNoDataProtocolContentPolicy.cpp

@@ -67,7 +67,7 @@ nsNoDataProtocolContentPolicy::ShouldLoad(PRUint32 aContentType,
   *aDecision = nsIContentPolicy::ACCEPT;
 
   // Don't block for TYPE_OBJECT since such URIs are sometimes loaded by the
-  // plugin, so they don't neccesarily open external apps
+  // plugin, so they don't necessarily open external apps
   if (aContentType != TYPE_DOCUMENT &&
       aContentType != TYPE_SUBDOCUMENT &&
       aContentType != TYPE_OBJECT) {

content/xslt/src/xpath/txExprParser.cpp

@@ -145,7 +145,7 @@ txExprParser::createAVT(const nsSubstring& aAttrValue,
             }
         }
         
-        // Add expression, create a concat() call if neccesary
+        // Add expression, create a concat() call if necessary
         if (!expr) {
             expr = newExpr;
         }

layout/generic/nsFrame.cpp

@@ -94,7 +94,7 @@
 #include "nsFrameTraversal.h"
 #include "nsStyleChangeList.h"
 #include "nsIDOMRange.h"
-#include "nsITableLayout.h"    //selection neccesity
+#include "nsITableLayout.h"    //selection necessity
 #include "nsITableCellLayout.h"//  "
 #include "nsITextControlFrame.h"
 #include "nsINameSpaceManager.h"