Internalize strings in-place

src/profiler/heap-snapshot-generator.cc

Index: src/profiler/heap-snapshot-generator.cc
diff --git a/src/profiler/heap-snapshot-generator.cc b/src/profiler/heap-snapshot-generator.cc
index fbb4e973d6157e65f4fb30ee94ea7a9f7809a4f8..c84892b069d6a7c28b3224136bbf35a6759fee0e 100644
--- a/src/profiler/heap-snapshot-generator.cc
+++ b/src/profiler/heap-snapshot-generator.cc
@@ -1165,6 +1165,10 @@ void V8HeapExplorer::ExtractStringReferences(int entry, String* string) {
     SlicedString* ss = SlicedString::cast(string);
     SetInternalReference(ss, entry, "parent", ss->parent(),
                          SlicedString::kParentOffset);
+  } else if (string->IsThinString()) {
+    ThinString* ts = ThinString::cast(string);
+    SetInternalReference(ts, entry, "actual", ts->actual(),
+                         ThinString::kActualOffset);
   }
 }