Bug 1482279 - Update the comment in dom/quota/test/common/content.js. r=asuth

Since content has no access to chrome-privileged objects without permissive
COWs, we can no longer unwrap the methods anymore. On the other hand,
SpecialPowers wrapper improved so that we don't have to unwrap the return
value from getAsArrayBuffer() manually.

Differential Revision: https://phabricator.services.mozilla.com/D79140

dom/quota/test/common/content.js

@@ -29,10 +29,11 @@ function clearAllDatabases(callback) {
 //
 // Our use of (wrapped) SpecialPowers.Cc results in getSimpleDatabase()
 // producing a wrapped nsISDBConnection instance.  The nsISDBResult instances
-// exposed on the (wrapped) nsISDBRequest are also wrapped, so our
-// requestFinished helper wraps the results in helper objects that behave the
-// same as the result, automatically unwrapping the wrapped array/arraybuffer
-// results.
+// exposed on the (wrapped) nsISDBRequest are also wrapped.
+// In particular, the wrapper takes responsibility for automatically cloning
+// the ArrayBuffer returned by nsISDBResult.getAsArrayBuffer into the content
+// compartment (rather than wrapping it) so that constructing a Uint8Array
+// from it will succeed.
 
 function getSimpleDatabase() {
   let connection = SpecialPowers.Cc[