Fix size_t to int conversion.

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index fb24bcce585c802450a500b8b5000c5aa445058b..ed4a501619a649e93a3872e34f0834279e189585 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -1625,9 +1625,9 @@ class StartupDataHandler {
     rewind(file);
 
     startup_data->data = new char[startup_data->raw_size];
-    startup_data->compressed_size = fread(
-        const_cast<char*>(startup_data->data), 1, startup_data->raw_size,
-        file);
+    startup_data->compressed_size =
+        static_cast<int>(fread(const_cast<char*>(startup_data->data), 1,
+                               startup_data->raw_size, file));
     fclose(file);
 
     if (startup_data->raw_size == startup_data->compressed_size)