[turbofan] Enable optimization of top-level eval code.

This removes the explicit disabling of optimization for eval code. Such
code can by now be optimized by TurboFan. Note that the usual heuristics
in the AstNumberingVisitor still apply and will be used to choose the
effective optimization backend.

R=bmeurer@chromium.org

Review-Url: https://codereview.chromium.org/1962103003
Cr-Commit-Position: refs/heads/master@{#36156}

src/compiler.cc

@@ -1336,12 +1336,6 @@ MaybeHandle<JSFunction> Compiler::GetFunctionFromEval(
     if (shared_info.is_null()) {
       return MaybeHandle<JSFunction>();
     } else {
-      // Explicitly disable optimization for eval code. We're not yet prepared
-      // to handle eval-code in the optimizing compiler.
-      if (restriction != ONLY_SINGLE_FUNCTION_LITERAL) {
-        shared_info->DisableOptimization(kEval);
-      }
-
       // If caller is strict mode, the result must be in strict mode as well.
       DCHECK(is_sloppy(language_mode) ||
              is_strict(shared_info->language_mode()));