The text highlight code in InlineTextBox.cpp:666 does a highlight of the entire run instead of the part we're searching for. Attached patch passes the missing parameters to select only the appropriate portions.
Created attachment 16387 [details] A potential fix
Comment on attachment 16387 [details] A potential fix This fixes a bug in a code path that I wrote a long time ago for Safari's use, but which Safari no longer uses. r=me
Checked in r25761