An empty JSString is created with the m_is8Bit member clear. Therefore if an empty string is created and an 8 bit JSString is appended, the resulting JSString will have the 8 bit flag cleared but it should be 8 bit.
Created attachment 116244 [details] Patch
Comment on attachment 116244 [details] Patch What is the performance effect if any?
(In reply to comment #2) > (From update of attachment 116244 [details]) > What is the performance effect if any? BY itself, this patch is a wash. It provides a benefit together with other changes.
Committed r101148: <http://trac.webkit.org/changeset/101148>