Move public symbols to the root set.

src/factory.h

Index: src/factory.h
diff --git a/src/factory.h b/src/factory.h
index 96f50856953e3011d9e99df4a7265be992ab88ca..14158232916c16a1f2cbc5b73f119246f2684886 100644
--- a/src/factory.h
+++ b/src/factory.h
@@ -612,6 +612,14 @@ class Factory FINAL {
   PRIVATE_SYMBOL_LIST(SYMBOL_ACCESSOR)
 #undef SYMBOL_ACCESSOR
 
+#define SYMBOL_ACCESSOR(name, varname, description)             \
+  inline Handle<Symbol> name() {                                \
+    return Handle<Symbol>(bit_cast<Symbol**>(                   \
+        &isolate()->heap()->roots_[Heap::k##name##RootIndex])); \
+  }
+  PUBLIC_SYMBOL_LIST(SYMBOL_ACCESSOR)
+#undef SYMBOL_ACCESSOR
+
   inline void set_string_table(Handle<StringTable> table) {
     isolate()->heap()->set_string_table(*table);
   }