[ia32,root] Allow usage of ebx for register code only in 'neg'

Bug: v8:6666
Change-Id: I5af95a3e9dcffb4be26a8ffd2948784d2910d64a
Reviewed-on: https://chromium-review.googlesource.com/1242804Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56196}

src/ia32/assembler-ia32.cc

@@ -1103,6 +1103,7 @@ void Assembler::neg(Register dst) {
 }
 
 void Assembler::neg(Operand dst) {
+  AllowExplicitEbxAccessScope register_used_for_regcode(this);
   EnsureSpace ensure_space(this);
   EMIT(0xF7);
   emit_operand(ebx, dst);