Bug 140145 – Harden baseline JIT implementations of op_resolve_scope and op_get_from_scope against undefined scope register value

• Status: ASSIGNED
• Component: JavaScriptCore

[Michael Saboff]

Similar to the issue in https://bugs.webkit.org/show_bug.cgi?id=140033 for op_new_func*, the DFG could dead code eliminate the use of the scope register.  Upon OSR exit to the baseline JIT, the scope register would be undefined.  The code determined to be dead by the DFG is still executed in the baseline JIT.  An inspection of the code shows that op_resolve_scope and op_get_from_scope need to be hardened against an undefined scope value.