Disable DCHECK for external reference address uniqueness on Windows

src/snapshot/serializer-common.cc

Index: src/snapshot/serializer-common.cc
diff --git a/src/snapshot/serializer-common.cc b/src/snapshot/serializer-common.cc
index 05a18ab727cc5c91445a98a8b9880d2bf81d515b..5d931b2af5006af075aa28032f622f1faf3d7a9d 100644
--- a/src/snapshot/serializer-common.cc
+++ b/src/snapshot/serializer-common.cc
@@ -24,7 +24,11 @@ ExternalReferenceEncoder::ExternalReferenceEncoder(Isolate* isolate) {
     Address addr = table->address(i);
     // Ignore duplicate API references.
     if (table->is_api_reference(i) && !map_->Get(addr).IsNothing()) continue;
+#ifndef V8_OS_WIN
+    // TODO(yangguo): On Windows memcpy and memmove can end up at the same
+    // address due to ICF. See http://crbug.com/726896.
     DCHECK(map_->Get(addr).IsNothing());
+#endif
     map_->Set(addr, i);
     DCHECK(map_->Get(addr).IsJust());
   }