V8ValueConverter::ToV8Value should not trigger setters

BUG=606390

Review URL: https://codereview.chromium.org/1918793003

Cr-Commit-Position: refs/heads/master@{#390045}
    explicit Level(FromV8ValueState* state) : state_(state) {
      state_->max_recursion_depth_--;
    }

    explicit Level(FromV8ValueState* state) : state_(state) {
      state_->max_recursion_depth_--;
    }
