diff --git a/src/transitions-inl.h b/src/transitions-inl.h
index 3f8272ff9b..b34c894417 100644
--- a/src/transitions-inl.h
+++ b/src/transitions-inl.h
@@ -98,6 +98,17 @@ PropertyDetails TransitionsAccessor::GetTargetDetails(Name* name, Map* target) {
   return descriptors->GetDetails(descriptor);
 }
 
+// static
+PropertyDetails TransitionsAccessor::GetSimpleTargetDetails(Map* transition) {
+  return transition->GetLastDescriptorDetails();
+}
+
+// static
+Name* TransitionsAccessor::GetSimpleTransitionKey(Map* transition) {
+  int descriptor = transition->LastAdded();
+  return transition->instance_descriptors()->GetKey(descriptor);
+}
+
 // static
 Map* TransitionsAccessor::GetTargetFromRaw(MaybeObject raw) {
   return Map::cast(raw->GetHeapObjectAssumeWeak());
@@ -146,6 +157,15 @@ bool TransitionArray::GetTargetIfExists(int transition_number, Isolate* isolate,
   return true;
 }
 
+int TransitionArray::SearchNameForTesting(Name* name,
+                                          int* out_insertion_index) {
+  return SearchName(name, out_insertion_index);
+}
+
+int TransitionArray::SearchSpecial(Symbol* symbol, int* out_insertion_index) {
+  return SearchName(symbol, out_insertion_index);
+}
+
 int TransitionArray::SearchName(Name* name, int* out_insertion_index) {
   DCHECK(name->IsUniqueName());
   return internal::Search<ALL_ENTRIES>(this, name, number_of_entries(),
@@ -200,6 +220,14 @@ void TransitionArray::Set(int transition_number, Name* key,
   WeakFixedArray::Set(ToTargetIndex(transition_number), target);
 }
 
+Name* TransitionArray::GetSortedKey(int transition_number) {
+  return GetKey(transition_number);
+}
+
+int TransitionArray::number_of_entries() const {
+  return number_of_transitions();
+}
+
 int TransitionArray::Capacity() {
   if (length() <= kFirstIndex) return 0;
   return (length() - kFirstIndex) / kEntrySize;
diff --git a/src/transitions.h b/src/transitions.h
index dcb31dc966..197f4bddb5 100644
--- a/src/transitions.h
+++ b/src/transitions.h
@@ -145,14 +145,9 @@ class TransitionsAccessor {
   friend class MarkCompactCollector;  // For HasSimpleTransitionTo.
   friend class TransitionArray;
 
-  static inline PropertyDetails GetSimpleTargetDetails(Map* transition) {
-    return transition->GetLastDescriptorDetails();
-  }
+  static inline PropertyDetails GetSimpleTargetDetails(Map* transition);
 
-  static inline Name* GetSimpleTransitionKey(Map* transition) {
-    int descriptor = transition->LastAdded();
-    return transition->instance_descriptors()->GetKey(descriptor);
-  }
+  static inline Name* GetSimpleTransitionKey(Map* transition);
 
   static inline Map* GetTargetFromRaw(MaybeObject raw);
 
@@ -224,12 +219,11 @@ class TransitionArray : public WeakFixedArray {
                                 Map** target);
 
   // Required for templatized Search interface.
-  static const int kNotFound = -1;
-  Name* GetSortedKey(int transition_number) {
-    return GetKey(transition_number);
-  }
+  static constexpr int kNotFound = -1;
+
+  inline Name* GetSortedKey(int transition_number);
   int GetSortedKeyIndex(int transition_number) { return transition_number; }
-  inline int number_of_entries() const { return number_of_transitions(); }
+  inline int number_of_entries() const;
 #ifdef DEBUG
   bool IsSortedNoDuplicates(int valid_entries = -1);
 #endif
@@ -261,9 +255,7 @@ class TransitionArray : public WeakFixedArray {
   }
 
   inline int SearchNameForTesting(Name* name,
-                                  int* out_insertion_index = nullptr) {
-    return SearchName(name, out_insertion_index);
-  }
+                                  int* out_insertion_index = nullptr);
 
  private:
   friend class Factory;
@@ -303,9 +295,7 @@ class TransitionArray : public WeakFixedArray {
 
   // Search a non-property transition (like elements kind, observe or frozen
   // transitions).
-  inline int SearchSpecial(Symbol* symbol, int* out_insertion_index = nullptr) {
-    return SearchName(symbol, out_insertion_index);
-  }
+  inline int SearchSpecial(Symbol* symbol, int* out_insertion_index = nullptr);
   // Search a first transition for a given property name.
   inline int SearchName(Name* name, int* out_insertion_index = nullptr);
   int SearchDetails(int transition, PropertyKind kind,
diff --git a/tools/generate-header-include-checks.py b/tools/generate-header-include-checks.py
index a76be5be1c..e83648304b 100755
--- a/tools/generate-header-include-checks.py
+++ b/tools/generate-header-include-checks.py
@@ -28,8 +28,6 @@ OUT_DIR = os.path.join(V8_DIR, 'check-header-includes')
 AUTO_EXCLUDE = [
   # flag-definitions.h needs a mode set for being included.
   'src/flag-definitions.h',
-  # blacklist of headers we need to fix (https://crbug.com/v8/7965).
-  'src/transitions.h',
 ]
 AUTO_EXCLUDE_PATTERNS = [
   'src/base/atomicops_internals_.*',