[serializer] cache ICs only as code stubs with key.

src/snapshot/code-serializer.h

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_SNAPSHOT_CODE_SERIALIZER_H_
 #define V8_SNAPSHOT_CODE_SERIALIZER_H_
 
 #include "src/parsing/preparse-data.h"
 #include "src/snapshot/serializer.h"
 
@@ skipping 27 matching lines @@
     back_reference_map_.AddSourceString(source);
   }
 
   ~CodeSerializer() override { OutputStatistics("CodeSerializer"); }
 
   void SerializeObject(HeapObject* o, HowToCode how_to_code,
                        WhereToPoint where_to_point, int skip) override;
 
   void SerializeBuiltin(int builtin_index, HowToCode how_to_code,
                         WhereToPoint where_to_point);
-  void SerializeIC(Code* ic, HowToCode how_to_code,
-                   WhereToPoint where_to_point);
   void SerializeCodeStub(uint32_t stub_key, HowToCode how_to_code,
                          WhereToPoint where_to_point);
   void SerializeGeneric(HeapObject* heap_object, HowToCode how_to_code,
                         WhereToPoint where_to_point);
   int AddCodeStubKey(uint32_t stub_key);
 
   DisallowHeapAllocation no_gc_;
   String* source_;
   List<uint32_t> stub_keys_;
   DISALLOW_COPY_AND_ASSIGN(CodeSerializer);
@@ skipping 58 matching lines @@
   static const int kPayloadLengthOffset = kNumCodeStubKeysOffset + kInt32Size;
   static const int kChecksum1Offset = kPayloadLengthOffset + kInt32Size;
   static const int kChecksum2Offset = kChecksum1Offset + kInt32Size;
   static const int kHeaderSize = kChecksum2Offset + kInt32Size;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_SNAPSHOT_CODE_SERIALIZER_H_