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

MozReview-Commit-ID: GF0YXDwfA14

dom/script/ScriptLoader.cpp

@@ -2564,7 +2564,7 @@ ScriptLoader::ConvertToUTF16(nsIChannel* aChannel, const uint8_t* aData,
   }
 
   if (!unicodeDecoder && aDocument) {
-    unicodeDecoder = Encoding::ForName(aDocument->GetDocumentCharacterSet())
+    unicodeDecoder = aDocument->GetDocumentCharacterSet()
                        ->NewDecoderWithoutBOMHandling();
   }