[runtime] Introduce dedicated JSBoundFunction to represent bound functions.

src/profiler/heap-snapshot-generator.h

Index: src/profiler/heap-snapshot-generator.h
diff --git a/src/profiler/heap-snapshot-generator.h b/src/profiler/heap-snapshot-generator.h
index fd1cb63881f990d414b741af7b43dc5cb52fb32d..857f2401bf08cc5cccf6fd40bc3e8daadcd138c1 100644
--- a/src/profiler/heap-snapshot-generator.h
+++ b/src/profiler/heap-snapshot-generator.h
@@ -390,7 +390,6 @@ class V8HeapExplorer : public HeapEntriesAllocator {
   void ExtractAllocationSiteReferences(int entry, AllocationSite* site);
   void ExtractJSArrayBufferReferences(int entry, JSArrayBuffer* buffer);
   void ExtractFixedArrayReferences(int entry, FixedArray* array);
-  void ExtractClosureReferences(JSObject* js_obj, int entry);
   void ExtractPropertyReferences(JSObject* js_obj, int entry);
   void ExtractAccessorPairProperty(JSObject* js_obj, int entry, Name* key,
                                    Object* callback_obj, int field_offset = -1);