Bug 1373984 - Turn nsIDocument::mCharacterSet into mozilla::NotNull<const mozilla::Encoding*>. r=hsivonen

MozReview-Commit-ID: GF0YXDwfA14

dom/script/ScriptLoadHandler.cpp

@@ -228,8 +228,7 @@ ScriptLoadHandler::EnsureDecoder(nsIIncrementalStreamLoader* aLoader,
 
   // Get the charset from the charset of the document.
   if (mScriptLoader->mDocument) {
-    encoding =
-      Encoding::ForName(mScriptLoader->mDocument->GetDocumentCharacterSet());
+    encoding = mScriptLoader->mDocument->GetDocumentCharacterSet();
     mDecoder = encoding->NewDecoderWithoutBOMHandling();
     encoding->Name(oCharset);
     return true;