x86: A couple of minor changes for String.indexOf() inlining

1. Removed sequence of FlushReg + Clobber + LockTemp for
particular registers and added FlushAllRegs. I believe it will
make sources more readable and not affect the performance
too much.
2. Made MarkPossibleNullPointerException call unconditional

Change-Id: I817f77718e15ec76cae35cf9fb04c0e5dcfb2d16
1 file changed