The DFG string access code kicks in only when the 'this' operand has a string prediction during parsing. That will never happen. No operand has any predictions during parsing. Parsing doesn't have predictions. Predictions don't exist until after prediction propagation runs. Prediction propagation runs only after parsing completely finishes. So, we should remove prediction checks from the code in the parser that recognizes string intrinsics.
Created attachment 171593 [details] the patch
Landed in http://trac.webkit.org/changeset/133135