[turbofan] Make a non-const reference argument const

Bug: v8:9429
Change-Id: I4274206875edd61f36ac51c05d53158b6c1e17fd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1700072
Auto-Submit: Georg Neis <neis@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62701}

src/compiler/state-values-utils.cc

@@ -329,9 +329,7 @@ void StateValuesAccess::iterator::Pop() {
   current_depth_--;
 }
 
-
-bool StateValuesAccess::iterator::done() { return current_depth_ < 0; }
-
+bool StateValuesAccess::iterator::done() const { return current_depth_ < 0; }
 
 void StateValuesAccess::iterator::Advance() {
   Top()->Advance();
@@ -392,8 +390,7 @@ MachineType StateValuesAccess::iterator::type() {
   }
 }
 
-bool StateValuesAccess::iterator::operator!=(
-    iterator& other) {  // NOLINT(runtime/references)
+bool StateValuesAccess::iterator::operator!=(iterator const& other) {
   // We only allow comparison with end().
   CHECK(other.done());
   return !done();

src/compiler/state-values-utils.h

@@ -92,7 +92,7 @@ class V8_EXPORT_PRIVATE StateValuesAccess {
   class V8_EXPORT_PRIVATE iterator {
    public:
     // Bare minimum of operators needed for range iteration.
-    bool operator!=(iterator& other);  // NOLINT(runtime/references)
+    bool operator!=(iterator const& other);
     iterator& operator++();
     TypedNode operator*();
 
@@ -104,7 +104,7 @@ class V8_EXPORT_PRIVATE StateValuesAccess {
 
     Node* node();
     MachineType type();
-    bool done();
+    bool done() const;
     void Advance();
     void EnsureValid();