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, 3 deletions

diff --git a/parser/html/nsHtml5StreamParser.cpp b/parser/html/nsHtml5StreamParser.cpp
index 83bf4d8b6..ab4548125 100644
--- a/parser/html/nsHtml5StreamParser.cpp
+++ b/parser/html/nsHtml5StreamParser.cpp
@@ -1261,7 +1261,7 @@ nsHtml5StreamParser::PreferredForInternalEncodingDecl(nsACString& aEncoding)
 }
 
 bool
-nsHtml5StreamParser::internalEncodingDeclaration(nsString* aEncoding)
+nsHtml5StreamParser::internalEncodingDeclaration(nsHtml5String aEncoding)
 {
   // This code needs to stay in sync with
   // nsHtml5MetaScanner::tryCharset. Unfortunately, the
@@ -1270,9 +1270,10 @@ nsHtml5StreamParser::internalEncodingDeclaration(nsString* aEncoding)
   if (mCharsetSource >= kCharsetFromMetaTag) { // this threshold corresponds to "confident" in the HTML5 spec
     return false;
   }
-
+  nsString newEncoding16; // Not Auto, because using it to hold nsStringBuffer*
+  aEncoding.ToString(newEncoding16);
   nsAutoCString newEncoding;
-  CopyUTF16toUTF8(*aEncoding, newEncoding);
+  CopyUTF16toUTF8(newEncoding16, newEncoding);
 
   if (!PreferredForInternalEncodingDecl(newEncoding)) {
     return false;