Introduce a new non-heap-allocated type for holding nsStringBuffer* in the HTML parser.

An innerHTML setter profile shows about 10% of the time being spent under nsHtml5HtmlAttributes::clear, mostly deleting nsStrings.

1 files changed, 4 insertions, 2 deletions

diff --git a/parser/html/nsHtml5MetaScannerCppSupplement.h b/parser/html/nsHtml5MetaScannerCppSupplement.h
index 5e7033777..9d2496361 100644
--- a/parser/html/nsHtml5MetaScannerCppSupplement.h
+++ b/parser/html/nsHtml5MetaScannerCppSupplement.h
@@ -19,13 +19,15 @@ nsHtml5MetaScanner::sniff(nsHtml5ByteReadable* bytes, nsACString& charset)
 }
 
 bool
-nsHtml5MetaScanner::tryCharset(nsString* charset)
+nsHtml5MetaScanner::tryCharset(nsHtml5String charset)
 {
   // This code needs to stay in sync with
   // nsHtml5StreamParser::internalEncodingDeclaration. Unfortunately, the
   // trickery with member fields here leads to some copy-paste reuse. :-(
   nsAutoCString label;
-  CopyUTF16toUTF8(*charset, label);
+  nsString charset16; // Not Auto, because using it to hold nsStringBuffer*
+  charset.ToString(charset16);
+  CopyUTF16toUTF8(charset16, label);
   nsAutoCString encoding;
   if (!EncodingUtils::FindEncodingForLabel(label, encoding)) {
     return false;