[clang] Use -Wshorten-64-to-32 to enable warnings about 64bit to 32bit truncations.

tools/shell-utils.h

Index: tools/shell-utils.h
diff --git a/tools/shell-utils.h b/tools/shell-utils.h
index 7b51d2f5b01468846e7e7e588b5aded5e137d514..31bd8ea8f68df45f42cb39a18b3949baca222e83 100644
--- a/tools/shell-utils.h
+++ b/tools/shell-utils.h
@@ -27,6 +27,8 @@
 
 // Utility functions used by parser-shell.
 
+#include "src/globals.h"
+
 #include <stdio.h>
 
 namespace v8 {
@@ -44,7 +46,7 @@ const byte* ReadFileAndRepeat(const char* name, int* size, int repeat) {
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);
-  int file_size = ftell(file);
+  int file_size = static_cast<int>(ftell(file));
   rewind(file);
 
   *size = file_size * repeat;