Fix cluster-fuzz found regression in d8 Workers

src/d8.cc

 // Copyright 2012 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.
 
 
 // Defined when linking against shared lib on Windows.
 #if defined(USING_V8_SHARED) && !defined(V8_SHARED)
 #define V8_SHARED
 #endif
 
@@ skipping 1560 matching lines @@
   Write(index);
 }
 
 
 SerializationTag SerializationData::ReadTag(int* offset) const {
   return static_cast<SerializationTag>(Read<uint8_t>(offset));
 }
 
 
 void SerializationData::ReadMemory(void* p, int length, int* offset) const {
-  memcpy(p, &data[*offset], length);
-  (*offset) += length;
+  if (length > 0) {
+    memcpy(p, &data[*offset], length);
+    (*offset) += length;
+  }
 }
 
 
 void SerializationData::ReadArrayBufferContents(ArrayBuffer::Contents* contents,
                                                 int* offset) const {
   int index = Read<int>(offset);
   DCHECK(index < array_buffer_contents.length());
   *contents = array_buffer_contents[index];
 }
 
@@ skipping 839 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif