message: Clean up, less nesting of nested if statements.
diff: @@ -39,19 +39,12 @@ bool IsTrivialOp(const NodeDef& node, const GraphRewriter& rewriter) {
  return true;
  }
  if (IsIdentity(node) || IsIdentityNSingleInput(node)) {
  - if (rewriter.FeedsMerge(node) || rewriter.IsDrivenBySwitch(node) ||
  + return !(rewriter.FeedsMerge(node) || rewriter.IsDrivenBySwitch(node) ||
  rewriter.IsDrivenByControlDependency(node) ||
  - rewriter.DrivesControlDependency(node)) {
  - return false;
  - } else {
  - return true;
  - }
  - }
  - if (IsAddN(node) && NumNonControlInputs(node) <= 1) {
  - return true;
  + rewriter.DrivesControlDependency(node));
  }
  - return false;
  + return IsAddN(node) && NumNonControlInputs(node) <= 1;
  }
  absl::flat_hash_map<string, absl::flat_hash_set<int>> IdentityNTerminalPorts(
  