update _.eq function comment

underscore.js

@@ -1184,7 +1184,7 @@
     // Identical objects are equal. `0 === -0`, but they aren't identical.
     // See the [Harmony `egal` proposal](http://wiki.ecmascript.org/doku.php?id=harmony:egal).
     if (a === b) return a !== 0 || 1 / a === 1 / b;
-    // A strict comparison is necessary because `null == undefined`.
+    // `null` or `undefined` only equal to itself (strict comparison).
     if (a == null || b == null) return false;
     // `NaN`s are equivalent, but non-reflexive.
     if (a !== a) return b !== b;