Adding fast path for generalizing maps.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 4b5b51d9d90e2363c3542c877a5489f8ddb7203d..0111c731c0233fcac516293e2d45e632672b2315 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2809,6 +2809,11 @@ class DescriptorArray: public FixedArray {
                                      int new_size,
                                      DescriptorArray* other);
 
+  bool IsMoreGeneralThan(int verbatim,
+                         int valid,
+                         int new_size,
+                         DescriptorArray* other);
+
   MUST_USE_RESULT MaybeObject* CopyUpTo(int enumeration_index);
 
   // Sort the instance descriptors by the hash codes of their keys.